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Base Stones
 Cobalt
Chemistry:
Co, elemental cobalt
Class: Elements
Subclass: Native Metals
Uses: Many applications for metallic cobalt.
Specimens
Cobalt has yet to be found in nature, but is being grown in laboratories
and these cobalt specimens are starting to appear in rock shops. Since
it has never been found in nature it is technically not a mineral although
lab grown specimens can look like a natural stone.
The element
cobalt has many industrial uses especially in dyes and in magnets. As
a dye, cobalt produces a spectacular blue color that is used most
notably
in glass and ceramics. When alloyed with iron and nickel, cobalt produces
a strong magnet. Cobalt has many uses in certain alloys for airplane parts
and engines.
Physical Characteristics:
Color is steel grey.
Luster is metallic.
Transparency: Specimens are opaque.
Crystal System is isometric.
Crystal Habits include only lab grown specimens.
Specific Gravity is 8.9 (very heavy for a metallic mineral).
Other Characteristics: Magnetic.
Notable Occurrences include only lab grown specimens.
Best Field Indicators are color, magnetism and density.
 Copper
Chemistry:
Cu, Elemental Copper
Class: Elements
Group: Gold
Uses: Minor ore of copper, ornamental stone
Native copper (copper found in a chemically uncombined state) has been
mined for centuries and now is all but depleted as an economically viable
ore. Other copper minerals are far more economical to mine and purify
into metallic copper that is used for wiring, electrical components, pennies
and other coins, tubing and many other applications. Native copper is
still found in limited quantities in once-active mining regions. These
finds are now valuable as minerological specimens and ornamental pieces.
Fine specimens only rarely demonstrate crystal faces and these are prized
above otherwise similar specimens.
Physical Characteristics:
Color is copper colored with weathered specimens tarnished green.
Luster is metallic.
Transparency is opaque.
Crystal System is isometric; 4/m bar 3 2/m
Crystal Habits include massive, wires and arborescent or branching forms
as the most common, whole individual crystals are extremely rare but when
present are usually cubes and octahedrons. Occasionally, massive forms
will show some recognizable crystal faces on outer surfaces.
Cleavage is absent.
Fracture is jagged.
Streak is reddish copper color.
Hardness is 2.5-3
Specific Gravity is 8.9+ (above average for metallic)
Associated Minerals are silver, calcite, malachite and other secondary
copper minerals.
Other Characteristics: ductile, malleable and sectile, meaning it can
be pounded into other shapes, stretched into a wire and cut into slices.
Best Field Indicators are color, ductility and crystal habit.
 Gold
Chemistry:
Au, Elemental gold
Class: Elements
Group: Gold
Uses: Major ore of gold and as mineral specimens.
Gold is a pleasure to own and possess, as many people have discovered
throughout the ages and around the world. Gold is a very stubborn element
when it comes to reacting to or combining with other elements. Keeping
this in mind, helps to explain many things about gold. There are very
few
true gold ores, besides native gold, because it forms a major part of
only a few rare minerals, it is found as little more than a trace in a
few others or it is alloyed to a small extent with other metals such as
silver. Gold is almost indestructible and has been used and then reused
for centuries to the extent that all gold of known existence is almost
equal to all the gold that has ever been mined. Gold is a great medium
metal for jewelry, as it never tarnishes. Native gold wires emerging from
massive white quartz can make for a visually stunning specimen.
A few of
the minerals that bear gold in their respective formulas are in a subclass
of sulfides called the tellurides. The element gold seems to have an affinity
for tellurium and this is one of the only elements that gold can bond
with easily. In fact only a few rare tellurides are found with out gold.
A few of the tellurides are nagyagite, calaverite, sylvanite and krennerite.
These are all minor ores of gold but their contributions to the supply
of gold pales next to native gold's own contribution. Occasionally these
minerals are associated with native gold.
There are
a number of minerals that are aptly named "Fool's Gold" because
only a fool could believe they are gold! Actually it is easy for people
who see shiny golden colored flakes sparkling at them from some rock they
just picked up to believe that they have struck pay-dirt. Gold's ductility,
sectility, density and softness are usually sufficient to distinguish
it from the much cheaper imposters. The most famous "fool's gold"
is the very common sulfide, pyrite. Chalcopyrite, marcasite and just about
any golden colored sulfide has been also proven to be worthy the "fool's
gold" monicure. Weathered flakes of biotite which can sport a bright
yellow color and a nice flash of light when viewed just right, have also
been mistaken for gold.
Gold specimens
are sometimes artistically stunning and a good investment as well. After
all, it is gold, which never seems to lose its value. Good natural specimens
though are more expensive than their actual weight value. This is to be
expected as good gold crystals are somewhat scarce (most are melted down
for quick profits) and you really don't want a natural specimen to be
worth what a lump of previously smelted and refined gold is worth, do
you?.
Physical characteristics:
Color is golden "butter" yellow.
Luster is metallic.
Transparency is opaque.
Crystal System is isometric; 4/m bar 3 2/m
Crystal Habits include massive nuggets and disseminated grains. Also wires,
dendritic and arborescent crystal clusters.
Cleavage is absent.
Fracture is jagged.
Streak is golden yellow.
Hardness is 2.5 - 3
Specific Gravity is 19.3+ (extremely heavy even for metallic minerals)
Associated Minerals include quartz, nagyagite, calaverite, sylvanite,
krennerite, pyrite and other sulfides.
Other Characteristics: ductile, malleable and sectile, meaning it can
be pounded into other shapes, stretched into a wire and cut into slices.
Best Field Indicators are color, density, hardness, sectility, malleability
and ductility
 Silver
Chemistry: Ag, Elemental silver
Class: Elements
Group: Gold
Uses: Minor ore of silver for use in jewelry, coins and
photographic films and other industrial uses.
Silver has been mined for eons and has always been popular in jewelry
and for coinage. Only in the past hundred years however, has the demand
for silver been so great. The reason for this demand is the use of silver
in the photography industry, which takes advantage of silver's reactivity
to light. Native Silver is rare and much silver is produced from silver-bearing
minerals such as prousite, pyrargyrite, galena, etc. Specimens of Native
Silver usually consist of wires that are curved and intertwined together,
making an inspiring mineralogical curiosity.
Physical Characteristics:
Color is silver white with exposed specimens tarnishing black.
Luster is metallic.
Transparency is opaque.
Crystal System is isometric; 4/m bar 3 2/m
Crystal Habits include massive and disseminated grains, wires and plates
as the most common, whole individual crystals are extremely rare but when
present are usually cubes, dodecahedrons and octahedrons. "Jack Frost"
type crystal growth as shown on some specimens produces beautiful intricate
structures. Wires can form coiled clusters that resemble rams horns.
Cleavage is absent.
Fracture is jagged.
Streak is silver white.
Hardness is 2.5-3.
Specific Gravity is variable according to purity 10-12 (well above average
even for metallic minerals)
Associated Minerals are silver minerals such as acanthite and prousite,
cobaltite, copper, zeolites and quartz.
Other Characteristics: ductile, malleable and sectile, meaning it can
be pounded into other shapes, stretched into a wire and cut into slices.
Best Field Indicators are color, tarnish, ductility and crystal habit.
 Tin
Chemistry:
Sn, elemental tin
Class: Native Elements
Subclass: Native Metals
Uses: Many applications for metallic tin.
Native tin (the latin word for tin is stannum and gives tin its chemical
symbol Sn) is a rare mineral. It is so rare that it in no way can it be
thought of as an ore of tin. Tin ore minerals include the oxide minerals
cassiterite and rutile and a few sufides such as franckeite, cylindrite,
canfieldite, stannite and teallite. By far the most tin comes from cassiterite;
SnO2. The largest tin producers are China and Indonesia followed by Peru,
Brazil, Bolivia and Australia. The United States which has significant
resources for most industrial metals is found quite lacking in tin. Alaska
has the only viable source of tin in the United States and it is insignificant
compared to other world sources.
Pure tin
metal has few uses and thus most tin is used in alloys. The most famous
tin alloy is bronze. Roughly 5% tin smelted with 95% copper produces bronze.
The development of bronze by primative humans was considered such an advancement
that the era was called the "Bronze Age". Most solder is a combination
of tin and lead. Another alloy of tin is pewter. Tin alloys had been used
to make tin cans and tin roofs, but they are not used for those purposes
too often now. Today, tin has significant use as a corrosion fighter in
the protection of other metals and alloys and in use in the glass making
industry as well as many other varied uses.
Native tin
is found in placer deposits and in unusual igneous intrusions. Australia
has the recognized type locality, but there is a report from Russia of
an earlier find. Tin is too rare to be seen in typical rock shops, but
laboratory specimens are being grown and put up for sale.
Physical characteristics:
Color is white to gray.
Luster is metallic.
Transparency: Specimens are opaque.
Crystal System is tetragonal (below 13.2 degrees C tin converts to isometric).
Crystal Habits include grains in placer deposits and lab grown specimens.
Cleavage is indistinct.
Hardness is 1.5 - 2.
Specific Gravity is 7.3 (heavy even for a metallic mineral).
Streak: white - gray.
Other Characteristics: Sectile.
Associated Minerals include native gold, native copper, stistaite, native
aluminum and other rare native metals.
Best Field Indicators are color, brittleness, hardness, locality and density.
 Zinc
Chemistry: Zn, elemental zinc
Class: Native Elements
Subclass: Native Metals
Uses: Many applications for the metal - zinc.
Native zinc is a rare mineral. Native zinc has been found in several locations
but is never found in any abundance. It would be wrong to consider it
an ore of zinc. First of all, an ore should be less valuable than its
constituent metal. And since zinc is so rare in its native form, this
is not true. Secondly, an ore needs to be common enough and exploitable
enough to be profitable enough to mine. In other words, economical! As
already stated, native zinc is a rare mineral and in addition, it does
not group itself in any siginificant concentrations. Actual ores of zinc
include sphalerite, smithsonite, hemimorphite, franklinite, willemite,
hydrozincite and zincite. Zinc is used in a variety of special alloys
that have unique industrial properties from great strength to unusual
plasticity.
Native zinc's
type locality is somewhat in doubt as different localities are sometimes
mentioned. The Mina Dulcinea de Llampos, Copiapo, Chile locality seems
to be the current type locality of concensus, however a case has been
made for the first specimens of native zinc actually coming from New Brunswick,
Victoria, Australia in 1855. Native zinc is found as indistinct grains
in igneous rocks with originations from a reducing environment.
As an important
industrial metal, zinc has been used for eons, even if its users did not
know what it was. It was used to make the zinc/copper alloy brass in prehistoric
times. A figure in the Bible, Tubal-cain, was mentioned as an instructor
in brass and iron. The Bible says he was 7 genenerations from Adam. Prehistoric
brass has been found in Romanian ruins. Romans made great use of brass
and found it to be ornamental as well as useful. It is doubtful that the
zinc metal was actually seen by its early users as it boils well below
copper's melting point and thus can not be melted into the copper. More
likely a technique was used that roasted the zinc ores with the copper
and the resultant zinc fumes absorbed into the melting copper.
There are
a few naturally occurring zinc alloys that are classified in the Elements
Class with native zinc. Naturally occurring brass, Cu3Zn2, is one of them.
It is being given consideration as a mineral, but is not yet officially
recognized. Other zinc alloy minerals include danbaite, CuZn2 and zhanghengite,
(Cu, Zn, Fe, Al, Cr).
Physical characteristics:
Color is white to bright blue gray.
Luster is metallic.
Transparency: Specimens are opaque.
Crystal System is hexagonal; 6/m 2/m 2/m.
Crystal Habits include volcanic exhalations, granular (often microscopic)
and lab grown specimens.
Cleavage is perfect in one direction (basal).
Hardness is 2.
Specific Gravity is 6.9 - 7.2 (heavy even for a metallic mineral).
Streak: Light gray.
Other Characteristics: Brittle at room temperatures (not malleable or
ductile unless heated to 100 degrees C).
Associated Minerals include native gold, native copper, native aluminum
and other rare native metals.
Best Field Indicators are color, brittleness, hardness, locality and density.
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