Originally, most landownership con-cerned land in its entirety; this type of ownership was called “fee ownership” and implied both surface own-ership and mineral ownown-ership all the wa
Trang 1Surface Versus Mineral Ownership
Much of the individually owned minerals in the
United States have resulted from original U.S
govern-ment patents and land grants to institutions and
private entities Originally, most landownership
con-cerned land in its entirety; this type of ownership was
called “fee ownership” and implied both surface
own-ership and mineral ownown-ership all the way down to the
center of the Earth Subsequent land transactions
have subdivided fee ownership into smaller tracts as well as separating (“severing”) surface ownership from mineral ownership It is also com-mon to find private surface owner-ship overlying government-owned mineral ownership The reverse is rare Sometimes the government-owned minerals in areas of extensive mining activity have been inadver-tently extracted because of confu-sion as to the rightful owner Mineral ownership can be nebu-lous and is not as closely defined and monitored in some situations as is surface ownership As a result, even basic property tax obligations may
be ignored through misunderstand-ings so that mineral property is often
“orphaned” by rightful owners and can be secured by more knowledge-able individuals by paying the taxes due or otherwise convincing the lo-cal property assessor that they are
in possession of the mineral owner-ship The folklore of mineral prop-erty ownership is filled with stories of the incidental property transfer that leads to vast wealth for the acquirer through subsequent mineral extrac-tion Although surface property has been known to escalate to hundreds
or even thousands of times its initial value, mineral ownership can result
in a million or more times its original value through proceeds from miner-als extraction Yet the management
of mineral ownership is often not of primary importance to the individ-ual because its value is frequently misunderstood
The separation of surface from mineral owner-ship often creates a unique set of problems If min-eral owners have the opportunity to have their miner-als extracted, the consequence to the surface owner must be considered In some states, the mineral owner has “primacy” such that reasonable access to the min-erals must be provided; the surface owner must be compensated for damages resulting from mineral-extraction activities In some areas where mineral
This is a gas well on the Crow Nation American Indian reservation in Montana
How-ever, the government—and not the tribe—possesses mineral rights because the land is
di-vided between aboveground and belowground ownership, a common process in the
Ameri-can West (Reuters/Landov)
Trang 2extraction is not feasible from surface operations,
such as in urban or environmentally sensitive sites, the
fate of mineral ownership may be determined in
courts of law
Mineral ownership in many remote areas across
the United States has minimal value because no
iden-tifiable commercial minerals are evident, or, if they
are present, they are too far from markets to have
value In areas of extensive mineral extraction, such as
traditional mining provinces or in oil and gas fields,
mineral ownership is closely protected and its
subdivi-sion complicated In these areas, the severance of
mineral types, depths, and locations is common For
example, if multiple coal deposits exist from the
sur-face to depth, the individual deposits may be
identi-fied as to ownership In southern Illinois, for
exam-ple, the many shallow coal deposits are exclusively
reserved for mining, while deeper coal deposits are
used for coal-bed methane extraction through drilled
wells In oil and gas areas, producing formations are
identified and may be separated as to ownership
Fre-quently, a shallow oil and gas zone may be included in
a lease along with deeper zones A time limit is
im-posed on the development of the shallow zone such
that it reverts to the mineral owner if not exploited
Oil and gas developers may be surprised to learn that
they cannot exploit the shallow zone even after
com-mitting funds to it Individual minerals may be
sepa-rated as well, with coal, oil, natural gas, sulfur, metallic
minerals, and industrial minerals being identified as
individual entities
Transactions and Appraisals
Mineral ownership can be exchanged through
like-kind trades or exchanges for virtually anything of
value The appraisal of mineral ownership is a
fre-quent activity but involves specialized training Since
many estates contain mineral ownership, the payment
of estate taxes depends on an appraisal of the mineral
ownership As compared with surface ownership,
which may often be appraised through comparable
sales, mineral transactions may be so rare in some
ar-eas as to have no standard of comparison This fact
places an additional burden on the appraiser in
arriv-ing at an accurate evaluation
Mineral ownership may be appraised by
calculat-ing a discounted present value of future revenues
from mineral exploitation If active mineral
extrac-tion operaextrac-tions are under way on a tract, projecextrac-tion of
these activities into the future may be relatively
accu-rate If assumptions of minerals pricing and operating expenses are accurate, the appraisal of mineral own-ership may well depend on discounted present value calculations
Determination of Ownership The determination of mineral ownership is similar to determination of surface ownership Title searches are made by professionals who execute a study of the ownership history of a tract of mineral ownership A chain of title is made to determine if any “clouds” on the title are indicated and to recommend remedies to these deficiencies A title search may be very simple if the ownership is created from the original U.S pat-ent It can be extremely complicated if the mineral ownership has been involved in numerous transac-tions, its ownership subdivided, and its minerals sev-ered No mineral extraction operation, such as mining
or oil and gas drilling, is begun without a reasonable title opinion Otherwise, the mineral exploitation is at-risk as to the payment of proceeds to the right-ful owner as well as lawsuits from maligned mineral owners
Disputes involving mineral property ownership are common and include boundary disagreements, geo-logical misinterpretations, and depth disputes Even the classification of minerals sometimes involves liti-gation Mineral disputes can also be settled by me-diation or arbitration in lieu of court appearances The nature of dispute settlement may depend on the language agreed upon by parties in earlier transac-tions
Wealth is created by mineral ownership transac-tions as discussed above, where trades may increase the value of the ownership The greatest amount of wealth enhancement, however, usually results when
a royalty from minerals extraction is negotiated If the mineral deposit is large and valuable, the min-eral owner can realize millions of dollars in royalties from mineral extraction As an example, a coal de-posit 4 meters in thickness contains about 18,000 metric tons per hectare If a royalty is negotiated to
be $3 per metric ton, the proceeds to the mineral owner are $54,000 per hectare Only in developed suburban areas will surface property values be greater Even greater wealth can be generated in areas where solid minerals as well as oil and gas can be exploited This frequently occurs in the Appalachian Basin in the eastern United States as well as in the Rocky Mountains
Trang 3Mineral Leasing
If mineral leasing is desired, there are guidelines that
govern most lease transactions Mineral leases involve
a mineral owner, called a lessor, and a mineral
opera-tor or intermediary, called the lessee A mineral lease
usually contains a primary term, bonus, and royalty
rate The term is the time extent of the lease
agree-ment and can vary from one year to as much as ten
years Multiple-year leases may also involve delay
rent-als, or annual rental fees to retain the lease Others
are paid up at the outset of leasing, meaning that no
delay rentals are due for the primary term of the lease
Some leases also have extensions past the primary
term Oil and gas leases usually specify that a lease can
be held past the expiration of the primary term if
commercial production has been established and is
sustained with no cessation over a term, usually ninety
days Stone and coal mining leases do not usually have
a held-by-production clause, but rather provide for
protection of future mining activity by using
exten-sions to the primary term that can be unilaterally
re-quested by the lessee with suitable advance notice to
the lessor
Lease bonuses are defined as the amount of
consid-eration due to the lessor at the time of lease
execu-tion This amount varies with the value of the lease,
and it may be as little as zero or as much as thousands
of dollars per hectare In places where an oil and gas
“play” is under way, lease bonuses can be in the
thou-sands of dollars for land parcels no larger than town
lots On the other hand, tracts intended for pure
ex-ploration drilling (“wildcats”) may secure lease
bo-nuses of only one to five dollars per hectare if
any-thing Governmental agencies, such as the Bureau of
Land Management in the U.S Department of the
In-terior, often demand larger than average bonuses
be-cause they may control the fate of mineral
develop-ment
The most important part of a mineral lease is the
royalty This is the income accruing to the mineral
owner over the productive life of the lease Royalty
ar-rangements can be as varied as there are minerals and
areas of the United States, but these arrangements
of-ten involve a percentage of the minerals produced In
times past, the royalty was paid “in-kind,” meaning
that the royalty owner was issued the proportionate
share of the mineral in the same form as the operator
and could market or keep it for domestic use as
de-sired Modern operating practice, which usually
in-cludes long-term contracts for the marketing of
min-erals, provides the royalty owner with a percentage of the selling price Royalty percentages vary from 2 per-cent of the selling price in the rock and stone industry
to as high as 25 percent or even 30 percent in offshore oil and gas operations Coal mining has royalty rates
in the 5 percent to 10 percent range In most cases, there has been a tendency for royalty percentages to increase over the past several decades Another trend
in mineral leases is for the royalty interest to bear cer-tain expenses of operation, particularly if a very large development cost is necessary to jump-start the min-eral exploitation These are usually fees involved in re-fining or marketing the product
Measurement of the bulk mineral or even the basis for its pricing are often the cause of litigation where the royalties are based on selling price For example,
if the mineral commodity is sold to an affiliate, a
“sweetheart price” lower than fair-market value may result Endless disputes over property boundaries and language in mineral conveyance documents, leases, and deeds have given rise to a legal specialty in min-eral law and even to subspecialties such as oil and gas law
Certain clauses in leases protect the lessor from a mineral operator making a halfhearted effort to de-velop the lease One such clause requires timely devel-opment of the leased tract either through continuity
of production or, in the case of oil and gas develop-ment, the steady drilling of new wells to prevent forfei-ture of the lease
Development Priorities The question of mineral development priority fquently arises in areas having multiple mineral re-sources Interference is minimized if the minerals in question can be recovered simultaneously However, there are situations where the exploitation of a partic-ular mineral commodity must wait until another is fully exploited Examples of this include the extrac-tion of near-surface minerals or the recovery of deep minerals where the exploitation of one would com-promise the exploitation of the other
Even relatively simple situations can result in ex-pensive and time-consuming litigation Some mineral ownership assignment documents specify the “superi-ority” of certain mineral commodities and place pri-orities on their extraction If the purchase of mineral ownership is contemplated, the title search should re-veal whether exploitation priorities are specified As mentioned above, disputes involving mineral
Trang 4owner-ship and minerals development have been and still
are quite common for a number of practical reasons
Inaccuracies in land surveying, the evolution of
geo-logic nomenclature, the shifting of streambeds, and
dishonest transactions all create discord Attorneys
and experts in mineral development team to
con-vince regulatory agencies, courts of law, and
media-tors that the evidence supports their client’s claims
Sometimes, the evidence is clear-cut Most often,
how-ever, a judgment decision is necessary where the
evi-dence is far from perfect
Measurements and Disputes
A classic type of dispute in oil and gas development
involves the drilling of wells to drain underneath an
adjacent tract In the past, innumerable disputes
con-cerned this “hot oil” problem Modern drilling
tech-nology, with its downhole drilling motors, permits
drilling a vertical well and then directing it to the
hori-zontal in a prescribed radius of curvature, such that a
well could be 1,500 meters in depth and its bottom
could be 600 meters laterally from its surface location
These wells are “surveyed” by using dip and azimuth
tools in the drillhole to pinpoint the location of the
bottom of the hole at any time, thus preventing a
dis-pute over whether adjacent property rights are being
violated
Downhole depth surveys also ensure that the oil or
gas well has not penetrated a lower zone that is
sev-ered from upper zones in a multiple-pay area
Instru-ments can be used to determine whether an oil or gas
zone is being produced from any zone downhole
Both the potential inaccuracy of measuring devices
and the possibility of dishonest measurement of bulk
commodities typify the problems confronting a
min-eral owner seeking a royalty payment The production
of solid bulk minerals such as coal is determined by
weighing a truck or railroad car on a large
drive-through scale, then loading it and subtracting its
“tare” weight to determine the amount of solid
mate-rial being transported Liquid commodities such as
oil are measured by flow meters or storage tank
mea-surements Gaseous commodities such as natural gas
are measured by rotating meters or orifice plates All
these measurement systems contain inherent
inaccu-racies such that the systems must be “proved,” or
cali-brated against a measurement standard at regular
in-tervals
The measurement of solid or liquid minerals in
floating vessels such as barges is made by
displace-ment of the barge in water This is done by scaling its draft in water in an unloaded and loaded condition The draft per weight of cargo is then converted into tonnage
Timber Rights and Water Rights Other types of property rights may be seen in certain parts of the United States Examples of these rights are timber ownership and the right to use surface
or underground water resources The ownership of water resources is particularly important in the more arid areas of the Southwest, and legal battles are fre-quently fought over access to potable and irrigation water
Timber ownership is frequently bought and sold
in the southeast and northwest areas of the United States In areas where tree harvesting is a recurring endeavor, the right to grow timber is valuable and is often at odds with the extractive industries
Charles D Haynes
Further Reading
Barberis, Daniéle Negotiating Mining Agreements: Past,
Present, and Future Trends Boston: Kluwer Law
In-ternational, 1998
Braunstein, Michael Mineral Rights on the Public
Do-main Cincinnati, Ohio: Anderson, 1987.
Hughes, Richard V Oil Property Valuation 2d rev ed.
Huntington, N.Y.: R E Krieger, 1978
Lowe, John S Oil and Gas Law in a Nutshell 4th ed St.
Paul, Minn.: Thomson/West, 2003
_, et al Cases and Materials on Oil and Gas Law.
4th ed St Paul, Minn.: West Group, 2002
Maley, Terry S Mineral Law 6th ed Boise, Idaho:
Min-eral Land Publications, 1996
Mayer, Carl J., and George A Riley Public Domain,
Pri-vate Dominion: A History of Public Mineral Policy in America San Francisco: Sierra Club Books, 1985.
Muchow, David J., and William A Mogel, eds Energy
Law and Transactions 6 vols New York: Lexis,
1990-2001
Otto, James, et al Mining Royalties: A Global Study of
Their Impact on Investors, Government, and Civil Soci-ety Washington, D.C.: World Bank, 2006.
Thompson, Robert S., and John D Wright Oil Property
Evaluation Golden, Colo.: Thompson-Wright, 1984.
See also: Mineral Leasing Act; Oil and natural gas drilling and wells; Oil industry; Takings law and emi-nent domain; Timber industry; Water rights
Trang 5Mineral resource use, early
history of
Categories: Historical events and movements;
social, economic, and political issues
Beginning with the Stone Age, people have used
miner-als both to forge the material part of civilization and
to express their artistic natures.
Background
There were inventors and great thinkers in the family
tree of humankind many thousands of years before
recorded history began One of them was the first to
use a stone as a tool, which was an important step in the
ascent of humankind because it gave people greater
control over their world and their lives Someone was
the first to make a clay pot, the first to find a use for tar,
the first to beat native copper into a useful shape
Somewhere in Mesopotamia in the seventh
millen-nium b.c.e., someone invented the kiln A kiln is a
fur-nace that retains and focuses a fire’s heat and allows
the air flow to be controlled The kiln technology of
the eastern Mediterranean, Mesopotamia, and Egypt
was unsurpassed, and it was there that production
techniques for pottery, bricks, cement, glass, copper,
and iron were first mastered
Stone Tools
The oldest stone tools were crude and were made
from whatever rocks were at hand Later tools were
made from stones chosen because they could be
shaped by chipping and retain a sharp edge Flints,
cherts, and jaspers were among the most common
stones used Obsidian is more brittle than flint, but its
edge can be made very sharp When it was available
and there was someone skilled enough to work it,
ob-sidian was preferred for cutting tools
To shape a stone by chipping, a second stone may
be used to strike glancing blows along the edge of the
first stone Common stone tools include hand axes,
scrapers, flint knives, and awls (used to make holes in
hides) Stone points were fastened to spears and
ar-rows Sickles to cut grain were made by setting sharp
stone chips into wooden handles A hollow can be
formed in a stone by pecking with a hard sharp rock
Stone bowls, lamps, and traylike grindstones were
made with this procedure from limestone, sandstone,
granite, and basalt (Grain was ground by placing it in
the grindstone and then rubbing it with a smaller handheld stone.)
Building with Stone Because of the relative ease with which limestone and sandstone can be shaped, they are often used in build-ings Granite is more durable but is harder to shape Granite is formed from an underground mass of mol-ten rock that cools very slowly Limestone and sand-stone are sedimentary rocks Sediments turn to rock
as the pressure of overlying layers squeezes water from between the sediment particles As the water is driven out, compounds dissolved in the water come out of solution and cement the sediment particles together Calcite (calcium carbonate), silica (silicon dioxide) and hematite (iron oxide) are typical cementing agents
Limestone is mostly calcium carbonate It occa-sionally is precipitated as a shallow sea evaporates, but more often it is built up from shells of dead sea organ-isms A limestonelike sediment containing a large fraction of calcium magnesium carbonate is called do-lomite and is a little harder than limestone Lime-stone and dolomite subjected to sufficient heat and pressure become marble
With the passage of time, people became profi-cient at quarrying, shaping, and moving stone The great pyramid of Khufu was constructed about 2600 b.c.e It is 50 percent taller than the Statue of Liberty and is estimated to contain 2,300,000 stone blocks weighing an average of 2.3 metric tons each The core
is made from huge yellowish limestone blocks from a nearby quarry, while the outer face and the inner pas-sageways are of a finer limestone brought from far-ther away Khufu’s burial chamber lies deep within the pyramid and is built of granite from Asw3n The leaning tower of Pisa, another fine example of early stone construction, was begun in 1174 c.e., more than three thousand years after the construc-tion of the great pyramid The tower is constructed of white marble and has colored marble inlays on the ex-terior Its walls are nearly 4 meters thick at the base and taper to about half that at the top, 56 meters above the ground In spite of its pronounced tilt, it is a beautiful structure of arches and columns
Cement Gypsum is a soft rock that forms as a precipitate when
a restricted body of seawater evaporates Chemically,
it is hydrous calcium sulfate (“Hydrous” means that
Trang 6water molecules are incorporated into the mineral’s
crystal structure.) If powdered and heated to drive off
its water content, gypsum becomes the basic
ingredi-ent of mortar The Egyptians used gypsum mortar in
building the pyramids When limestone is heated in a
kiln, carbon dioxide is driven off, leaving quicklime
(calcium oxide) If clayey limestone is used, the
quick-lime will contain large amounts of silica and alumina
This mix is called hydraulic lime Adding water to
hy-draulic lime produces a cement that will set and
harden even underwater by forming calcium silicates
and aluminates The Romans produced a hydraulic
lime mortar called pozzolana by combining quick-lime with sand and powdered volcanic tuff mined near the Italian town of Pozzuoli Pozzolana was used
in the construction of the Colosseum at Rome
Building with Brick Construction stone is rare in the fertile land beside the Euphrates, so the ancient Mesopotamians built with bricks Ruins at Ur of the Chaldees have yielded both burned and unburned bricks that are five thou-sand years old Clay suitable for making bricks is found throughout the world Clay particles are very
The Sumerian temple of Ur, in present-day Iraq, is an early example of the use of brick, a by-product of clay, as a building material (The
Granger Collection, New York)
Trang 7fine and consist primarily of various forms of hydrous
aluminum silicates along with organic material and
other minerals Bricks are usually shaped in a mold
and then left in the sun to dry Dried bricks may then
be placed in a kiln for a process called “burning,” in
which they are heated enough to cause the clay
parti-cles to fuse
The ancient city of Babylon, which reached its
zenith under Nebuchadnezzar in the sixth century
b.c.e., was built with bricks Its massive outer wall was
built with a core of sun-dried brick and faced with
burned brick The famous Ishtar gate stood 12 meters
high and featured 575 glazed brick mosaics in which
golden dragons and young bulls stood out in relief
against a blue-green background One hundred twenty
golden lions on blue-green backgrounds lined the
walls of the street that led from the Ishtar gate to the
temple of Marduk
Pottery and Porcelain
Pottery making is probably as old as civilization itself
To be durable, a clay pot must be fired in a kiln so that
clay particles fuse and the glaze (if present) melts to
form a glassy surface In the Near East, pottery dating
back to the seventh millennium b.c.e has been
dis-covered Painted pottery was already common in
northern Mesopotamia before 5000 b.c.e., and the
high-speed potter’s wheel was used in ancient Susa by
4000 b.c.e About that same time, the Egyptians
be-gan working with colorful and lustrous glazes that
may have led them to the development of glass
Porcelain is a type of ceramic made from kaolin (a
special white clay with very few impurities), feldspar
(aluminum silicates), and quartz (silica) Porcelain
paste is stiff and harder to shape than normal clay
paste, but it retains its shape well at high
tempera-tures Because of this, porcelain pieces with very thin
walls can be made The Chinese became experts at
crafting porcelain pieces and in using colorful
enam-els and glazes to decorate them Vases made during
the Ming dynasty (1368-1644 c.e.) have become
leg-endary
Glass
Some of the oldest glass objects known are beads
found in an Egyptian tomb dated at 2500 b.c.e About
a thousand years later, the first glass vessels appear in
Egypt These vessels were made by winding a string of
glass around a clay mold held on the end of a rod The
technique of glassblowing was in use by the first
cen-tury b.c.e., although some tomb murals indicate it may have been used much earlier
The Romans were the first to use glass windows, and there are glass windows in the public baths of Pompeii, the city destroyed by an eruption of Mount Vesuvius in 79 c.e As they did with pottery, some ists created glass vessels of exquisite beauty Other art-ists turned their talents to stained-glass windows such
as those of the Sainte-Chapelle in Paris (consecrated
in 1248 c.e.) Its stained-glass windows depicting bibli-cal scenes completely dominate the walls and soar upward in a kaleidoscope of red, blue, green, yellow, and white
The chief constituent of glass is white sand (silica), but melting pure silica requires a temperature above 1,700° Celsius If soda ash (sodium carbonate) is added as a flux, the melting point is reduced to 850° Celsius, a temperature more easily achieved The re-sulting glass is water soluble, but adding limestone (calcium carbonate) to the melt results in insoluble glass A typical mixture is 75 percent silica, 10 percent lime, and 15 percent soda Soda ash can be obtained
by leaching wood or seaweed ash or by mining natron, another salt deposited as an entrapped sea evapo-rates
The Seven Metals of Antiquity
As far back as 8000 b.c.e., Stone Age people gathered shining bits of gold to use as ornaments and decora-tions Seams of gold in solid rock such as granite are called lode deposits They are mined by tunneling into the rock As gold-bearing rock weathers away, gold dust and gold nuggets wash into streambeds to form placer deposits Placer deposits may be mined by scooping up sand and gravel in a pan and then care-fully washing away everything but the dense grains of gold The story of Jason and the Golden Fleece proba-bly refers to the ancient practice of placing a fleece in running water where it could collect gold dust as placer deposit sand was washed over it The golden death mask of Tutankhamen (1352 b.c.e.) is an excel-lent example of the artistry with which gold was worked
in ancient times
Copper was discovered about the same time as gold, since it can also be found naturally as a metal Copper pins dating from 7000 b.c.e have been found
in Turkey Malachite is a green-colored copper ore of-ten found near a seam of copper metal Copper metal may be produced from malachite by mixing it with charcoal and heating the mixture in a kiln The
Trang 8earli-est tools cast from molten copper appear in
Mesopo-tamia around 4000 b.c.e
Lead may have been the next metal discovered,
since lead beads dated to 6500 b.c.e have been found
in Turkey Lead does not occur as a free metal in
na-ture, but the lead ore called galena (lead sulfide) does
have a metallic look If galena is combined with
char-coal and heated to only 327° Celsius, metallic lead is
produced Since lead is soft and ductile, the Romans
found it well suited for making pipes Lead often
con-tains traces of silver Silver artifacts date back to about
4000 b.c.e Metallic silver is rarely found in nature,
but it does occur Pure silver is harder than gold but
softer than copper As with gold, silver was first used to
make ornaments and jewelry
By 2500 b.c.e the Sumerians discovered that
mix-ing different types of ore produced a metal that melted
at a lower temperature and was harder than copper
They had produced a copper-tin alloy now called
bronze Bronze was widely used to make tools and
weapons Tin was not produced as a separate metal
until five hundred years later Tin ore is stannic oxide,
a hard material that remains after softer surrounding
rock weathers away Mercury can be obtained by
heat-ing cinnabar (mercury sulfide) in the presence of
oxy-gen Mercury has been found in tombs dating from
1500 b.c.e It is a liquid at room temperature and can
dissolve silver and gold to form an amalgam, a process
that is sometimes used in mining
Smelted iron did not become common until
around 1500 b.c.e., although it was first produced one
thousand years earlier; meteoric iron was used even
before that Metallic iron may be produced by heating
a mixture of hematite (iron oxide) and charcoal in a
kiln Only the rich could afford bronze, but when iron
became cheaper than bronze, iron tools and weapons
were made in large numbers Being more broadly
dis-tributed through society than bronze, iron greatly
changed farming and warfare
Salt
Salt (sodium chloride) is essential for human health
It is generally accepted that a diet consisting mostly of
raw or roasted meat requires no added salt, but if the
meat is boiled or if the diet consists primarily of
grains, some salt is essential Salt has also been used as
a preservative for fish and meat since ancient times
People collected salt at brine springs or from dried
tidal pools at the seashore Later, ocean water was let
into artificial pools that were then sealed and allowed
to dry In colder climates salt water was boiled down in ceramic trays and later in metal trays Many areas of the world have underground salt beds formed as an-cient seas dried up Rock salt has been mined from such deposits beginning in Roman times, if not ear-lier
Petroleum Products and Natural Gas The use of petroleum goes back to the Stone Age, when bitumen was used to cement stones to wooden handles (“Bitumen,” loosely used, refers to various tars and asphalt.) The Sumerians, in 3000 b.c.e., and later the Assyrians and the Babylonians, used a mortar of bitumen, sand, and reeds for their great brick structures They also made asphalt roads, used tar as an adhesive for tiles, and caulked ships with tar Dioscorides, a surgeon in Nero’s army, said that the Sicilians burned petroleum oil in their lamps in place
of olive oil Eventually, petroleum grease was used as
a lubricant, paraffin wax was used for candles, and naphtha (a highly volatile oil) found use as an incen-diary agent in warfare
At first, bitumen was taken from natural tar pits and oil and gas seeps Three of the most famous are the La Brea Tar Pits of California, the Pitch Lake of Trinidad, and the Perpetual Fires of Baku, a large gas seep area
in Azerbaijan Later, oil was taken from tunnels and pits dug near oil seeps By the sixth century b.c.e., the Chinese could drill wells 100 meters deep While drill-ing for fresh water or salt water, Chinese miners occa-sionally found oil or natural gas instead This is exactly what happened to the Chinese while drilling for salt water in Sichuan about 250 c.e Being opportunists, the workers at some salt works burned the gas to pro-vide heat to evaporate the brine With the passage of time, the production and use of petroleum increased, but it did not become a major resource until kerosene became cheaper than whale oil in the mid-nineteenth century
Coal Coal is the fossilized remains of plants that lived hun-dreds of millions of years ago A coal bed begins as a thick layer of peat in a swamp that is later invaded by the advancing sea Layers of sediment compress the peat, which dries, hardens, and eventually turns into coal Coal consists primarily of carbon but also con-tains smaller amounts of water, light oil, tar, sulfur, and phosphorus
The Chinese are said to have used coal in the first
Trang 9century b.c.e., and in the thirteenth century c.e.
Marco Polo described a black stone that the Chinese
dug from the mountains and burned for fuel Polo
seems to have been unaware that coal was already
used in Europe and England In fact, Theophrastus
described various Mediterranean locations where coal
was used as fuel in the fourth century b.c.e Long
be-fore Polo’s time, “sea coal” was gathered regularly
from some of England’s beaches, where it washed
ashore, and coal was mined from shallow pits in other
regions However, Europeans used coal only on a
small scale until the fifteenth century c.e., when it
became widely used in kilns
Charles W Rogers
Further Reading
Agricola, Georgius De re metallica: Translated from the
First Latin Edition of 1556 with Biographical
Introduc-tion, Annotations and Appendices upon the Development
of Mining Methods, Metallurgical Processes, Geology,
Mineralogy and Mining Law from the Earliest Times to
the Sixteenth Century by Herbert Clark Hoover and Lou
Henry Hoover Reprint New York: Dover, 1986.
Buranelli, Vincent Gold: An Illustrated History
Maple-wood, N.J.: Hammond, 1979
Camusso, Lorenzo, and Sandro Bortone, eds Ceramics
of the World: From 4000 B.C to the Present New York:
H N Abrams, 1991
Craddock, Paul, and Janet Lang Mining and Metal
Pro-duction Through the Ages London: British Museum,
2003
Freese, Barbara Coal: A Human History Cambridge,
Mass.: Perseus, 2003
Hawkes, Jacquetta The Atlas of Early Man 1976
Re-print New York: St Martin’s Press, 1993
Lynch, Martin Mining in World History London:
Reak-tion, 2002
Macfarlane, Alan, and Gerry Martin Glass: A World
History Chicago: University of Chicago Press, 2002.
Multhauf, Robert P Neptune’s Gift: A History of Common
Salt Baltimore: Johns Hopkins University Press,
1978
Wertime, Theodore A., and James D Muhly, eds The
Coming of the Age of Iron New Haven, Conn.: Yale
University Press, 1980
See also: Brick; Bronze; Ceramics; Clays; Coal;
Cop-per; Glass; Gold; Iron; Lead; Mercury; Metals and
metallurgy; Native elements; Oil and natural gas
drill-ing and wells; Silver; Tin; Zinc
Minerals, structure and physical properties of
Category: Mineral and other nonliving resources
Minerals—naturally occurring inorganic solids with definite chemical composition and definite crystal structure—are the primary constituents of rocks; they are also found in soil The variety of minerals is huge, and their myriad applications range from use as gem-stones and precious metals to applications in building materials, electronics, food, and pharmaceuticals.
Background Minerals are the building blocks of rocks, and they have many economic uses Minerals such as diamond, ruby, emerald, and sapphire are precious gems Other minerals are valuable metals (gold, silver, platinum, copper) or metal ores, such as hematite (iron), sphalerite (zinc), galena (lead), and bauxite (alumi-num) Other minerals are used as salt (halite), lubri-cants (graphite), abrasives (corundum), and fertil-izer (apatite), as well as in pharmaceuticals (sulfur), steel making (fluorite), plaster (gypsum and anhy-drite), lime, and portland cement (calcite and dolo-mite)
A mineral is defined as a naturally occurring, inor-ganic solid with a definite chemical composition (or range of compositions within certain limits) that can
be expressed by a chemical formula, and an orderly internal crystalline structure (its atoms are arranged
in a definite pattern which is reflected in the shape of its crystals and in its cleavage) Only substances that meet these precise requirements are considered min-erals As a result, synthetic gems, which may be physi-cally and chemiphysi-cally identical to natural gemstones, are not considered minerals
Minerals have specific physical properties that re-sult from their chemical composition and crystal structure, and many minerals can be identified by these properties Physical properties include hard-ness, color, luster, streak, cleavage, density or specific gravity, and crystal form Some minerals also have additional diagnostic physical properties, including tenacity, taste, magnetism, electrical properties, lumi-nescence, reaction to hydrochloric acid, and radio-activity
Trang 10Hardness is a mineral’s resistance to scratching or
abrasion and is a result of crystal structure or atomic
arrangement The stronger the chemical bonds
be-tween the atoms, the harder the mineral For
exam-ple, two minerals may have an identical chemical
composition but different crystal structures, such as
diamond and graphite, which are both carbon
Dia-mond is the hardest known mineral, but graphite is so
soft that it rubs off on the fingers or a piece of paper
(it is used as pencil “lead”) The differences in crystal structure produce the vastly different hardnesses of these two minerals
Ten minerals have been arranged in order of in-creasing hardness and are referred to as the Mohs hardness scale, devised in 1822 by a German mineral-ogist, Friedrich Mohs The minerals of the Mohs hard-ness scale, in order from softest to hardest, are: (1) talc, (2) gypsum, (3) calcite, (4) fluorite, (5) apatite, (6) potassium feldspar (orthoclase), (7) quartz, (8)
Physical Properties of Minerals
Chemical composition Chemical formula that defines the mineral
Cleavage Tendency to break in smooth, flat planes along zones of weak bonding;
depends on structure Color Depends on presence of major elements in the chemical composition; may
be altered by trace elements or defects in structure; often not definitive Crystal shape Outward expression of the atomic crystal structure
Crystal structure Three-dimensional ordering of the atoms that form the mineral
Density Mass per unit volume (grams per cubic centimeter)
Electrical properties Properties having to do with electric charge; quartz, for example, is
piezoelectric (emits charge when squeezed) Fracture Tendency for irregular breakage (not along zones of weak bonding)
Hardness Resistance of mineral to scratching or abrasion; measured on a scale of 1-10
(Mohs hardness scale) Luminescence Emission of electromagnetic waves from mineral; some minerals are
fluorescent, some thermoluminescent Luster Reflectivity of the surface; may be either metallic or nonmetallic
Magnetism Degree to which mineral is attracted to a magnet
Radioactivity Instability of mineral; radioactive minerals are always isotopes
Specific gravity Relative density: ratio of weight of substance to weight of equal volume of
water at 4° Celsius Streak Color of powdered form; more definitive than color
Taste Salty, bitter, etc.; applies only to some minerals
Tenacity Resistance to bending, breakage, crushing, tearing: termed as brittle,
malleable, ductile, sectile, flexible, or elastic