Feldspar Minerals Feldspar Minerals: group of silicates;
mineral of crust, cleavage at 90 with flat, rectangular, glassy
surfaces 1. Albite ( Plagioclase): Plagioclase Feldspar: calcium to
sodium rich; example is albite; has striations (thin parallel
grooves) 2. Amazonite (Microcline) 3. Orthoclase Group: Orthoclase
Feldspar: Feldspar group; also known as potassium feldspar KAlSi 3
O 8
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Silicates Mica Group: silicate; perfect cleavage; in one
direction it splits into sheets; examples are muscovite (colorless
or silvery); biotite (black with magnesium and iron); lepidolite
(lilac or rose colored) Amphibole group: silicate; two directions
of cleavage not at 90; narrow elongated crystals; example is
hornblend ( dark contains magnesium and iron) Pyroxene group: two
directions of cleavage at 90; typically dark; example is augite(
dark with magnesium and iron)
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Other Minerals Clay mineral: Silicate; weathered feldspar; very
fine grained; earthy luster; smooth; example is Kaolinite
Non-Silicate Minerals: 8% of earths crust; element, oxides,
sulfides, etc. Carbonates: non silicate; example is calcite (CaCO 3
) with limestone and marble Halides & Sulfides: evaporate
minerals
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Classes of Silicates Sorosilicates Cyclosilicates Inosilicates
Phyllosicates Tectosilicates
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Extra Info Quartz or quartz crystal, a nearly pure silicon
dioxide specimen occurs in most igneous and practically all
metamorphic and sedimentary rocks. Lepidolite, muscovite, and
biotite exhibit cleavage with weak bonds in only one direction.
Halite is classified as an evaporite due to its having been formed
by the evaporation of saline water within partially enclosed
basins. Almandine garnet is able to overpower and displace
surrounding solid material during its formation so that it almost
always develops its characteristic crystal faces. Bornite or
chalcopyrite, often associated with the minerals sphalerite and
galena, is the main source of copper.
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Extra Info Sphalerite is a major source of zinc. Hematites
streak is always reddish brown in color in spite of its actual
color being brown, red or silver. Gold has a specific gravity of
19.3. Feldspar is the most common mineral found in Earths crust.
Opal is not a crystalline solid and is, instead, classified as a
mineraloid.
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Extra Info Galena is the primary source of lead. Staurolite
consists of a basic silicate of iron and aluminum in prismatic
orthorhom- bic crystals often twinned so as to resemble a cross.
Fluorite, represented by its more rare octahedral crystal form at
this station, occurs naturally in nearly every color of the
spectrum. Amazonite is a form of microcline named for a South
American rainforest where it is nowhere to be found. Ulexites
optical effect is created by individual fibers acting as
fiber-optic cables, transmitting light from one surface to the
other.
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Extra Info Sodalite has a pleasant blue color, usually includes
white veins or streaking, and is commonly used as a carving stone.
Rhodonite, a pink and red specimen, often has black manganese oxide
veins running through it, giving it a distinct appearance of pink
with black crisscrossing lines. Dolomites crystal habits include
saddle shaped rhombohedral twins and simple rhombs, some with
slightly curved faces. Beryl has several varieties, including the
emerald specimen at this station.
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What are the two most abundant elements by mass found in
Earth's crust? 1. aluminum and iron 2. sodium and chlorine 3.
calcium and carbon 4. oxygen and silicon
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Which mineral is white or colorless, has a hardness of 2.5, and
splits with cubic cleavage? calcite 2. halite 3.pyrite 4. Mica
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Common Minerals
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Hematite Used for mining iron ore Has a reddish brown streak
because of the iron and oxygen present, making rust Classified as
oxide Has higher specific gravity than corundum Streak test would
be a good test to identify; by crushing will notice blood red
powder Silver or gray in appearance When magnetite reacts with
oxygen, hematite will form Rich source of iron Hardeness: 5-6
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Goethite Used for mining iron ore Is classified as a
hydroxide
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Limonite Also called brown iron ore or brown hematite
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Tremolite Has another form, Asbestos, can be used as a fire
retardant
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Copper Native Element/Mineral Same hardness as bornite Is very
conductive Is used to make the alloy, Brass
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Bornite Same hardness as copper Is a copper, iron sulfide Is an
ore of copper Used in jewelry
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Corundum Is the 2nd hardest natural mineral known to man
Diamond is four times harder Used for abrasive and as a gemstone
Classified as oxide Mineral of rubies and sapphires Hexagonal
crystal system Hematite family Chemical formula: Al2O3 Hardness:
9
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Aragonite Carbonate mineral Is unstable at normal temperatures
at Earths surface Has magnesium in its composition Same chemical
formula as calcite and therefore is polymorph of calcite CaCO 3
Different crystalline structre than calcite; but when heated will
form calcite Softer than feldspar Orthorhombic Specific Gravity
2.94
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Calcite Carbonate mineral Transparent variety is called Iceland
spar Primary component of cave formation Same chemical formula as
aragonite and therefore is polymorph of aragonite Exhibits
effervesce Calcite is made by plankton and falls to bottom of sea
when plankton die
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Azurite Copper carbonate About same hardness as malachite
Classified as carbonate and thus related to calcite and dolomite
Classified as copper ores Used as pigments, minor ores of copper,
and ornamental Does not effervesce in hydrochloric acid
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Malachite Copper carbonate Can replace azurite over time About
same hardness as azurite More common than azurite classified as
carbonate and thus related to calcite and dolomite Classified as
copper ores Used as pigments, minor ores of copper, and ornamental
Will effervesce in diluted hydrochloric acid Crystal System:
Monoclinic
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Graphite Is primarily composed of carbon Can conduct
electricity on one plane of tetrahedrally bonded carbon atoms Main
function is lubricant Also used in pencils, control rods of nuclear
reactors, batteries Found in China, Brazil, Canada, Madagascar, Sri
Lanka Pure Deposits in Borrowdale, England Hexagonal crystal
system
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Silver Native Element The coating on the spoon Reacts with
sulfur and tarnishes Best conductor of electricity Crystal System:
Cubic Easily tarnished in air and is therefore rarely found in its
pure form
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Sphalerite Is a zinc, iron sulfide Hardness is a little harder
than copper Major ore of zinc Is commonly found in sedimentary
environments in evaporate deposits, volcanic activity When mixed
with sulfur and water produces hydrogen sulfide gas
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Sulfur Native Element When mixed with sphalerite and water
produces hydrogen sulfide gas Causes acid rain Used in pesticides,
gunpowder, and fungicides Crstal System: Orthorhombic
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Lepidolite Could be called a Potassium-Aluminum-Silicate Also
has a massive form and is often associated with tourmaline
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Muscovite Could be called a Potassium-Aluminum-Silicate
Elastic
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Biotite Could be called a Potassium-Aluminum-Silicate
Elastic
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Dolomite CaMg(CO 3 ) 2 rhombohedral cleavage Also known as
dolomite rock Constituent of dolostone Form alternative of
limestone with addition of magnesium Is a double carbonate and
therefore does not dissolve as rapidly or effervesce as rapidly as
calcite
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Gypsum Classified with evaporites, CaSO 4 2H 2 O Also known as
rock gypsum Used for plaster Generally soft Varieties include
selenite (clear with rhombohedral cleavage), alabaster (fine grain
and massive), satin spar (fibrous)
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Alabaster Gypsum Could be used to make Plaster of Paris Has the
mineral Calcium It could be used as a fertilizer.
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Epidote Classified as Sorosilicate mineral
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Olivine Magnesium Iron Sillicate mineral Crystal System:
Orthorhombic It could be used as an abrasive because of its
hardness It is found in many iron-nickel meteorites Is a
neosilicate Often glassy Exhibits conchoidal fractures Mg and Fe
rich Most abundant in earths mantle
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Quartz Silicate mineral Second most abundant of crust
Constituent in sandstone and quartzite Has conchoidal fracture
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Amethyst Major use is for jewelry, mineral A type of
quartz
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Kaolinite Used for medications, paper filler; make pottery Is
white and powdery
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Apatite Softer than feldspar It is part of your bone structure
and makes up the teeth of all vertebrates Used as plant fertilizers
to alter taste Main source of phosphate in world Crystal System:
hexagonal
Slide 40
Talc Made of hydrous magnesium silicate Used in lubricanys,
baby powder,plastics, and rubber, soapstone ornaments Crystal
System: monoclinic
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Fluorite Belongs to group of minerals containing halogens
Harder than halite, but appearance is same Used in iron smelting,
added to water to prevent kidney disease, lenses, nonstick coatings
Has same isometric crystal system as halite Has fluorescent
properties when under UV lights Made of Calcium Fluoride Crystal
System: cubic
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Halite Belongs to a group of minerals containing halogens Would
most likely be found where seas or lakes have dried up Same
isometric crystal system as fluorite Is necessary for the human
body NaCl evaporate Also called rock salt Has cubic cleavage Used
to melt ice Can be taken out of sea water or mined Found in
Germany, England, Poland and US
Slide 43
Galena Has a structure identical to halite An ore of lead
Classified as a sulfide Specific gravity is about two times heavier
than magnetite Specific gravity is about 7.5 times heavier than
that amount of water Is a natural semiconductor and is used in
televisions, GPS systems and telephones First used as kohl until
found to be poisonous
Slide 44
Pyrite Has structure analogous to galena Can be called Fools
gold or Sulfide mineral Golden or black streak Golden yellow in
color Grows in shiny cubes Found in Japan, Spain, US Used in
jewelry
Slide 45
Chalcopyrite Unlike pyrite, contains copper, and is a copper
iron sulfide Leading source of copper because it is found in large
quntities and distributed widely Also called fools gold or sulfide
Found in igneous rocks
Slide 46
Magnetite Has two forms of iron causing the electrons to
transfer between the different ions Specific gravity is about the
average for metallic minerals Classifiead as an iron oxide Can be
made into magnets Black or metallic Found South Africa, US, Sweden
on black sand beaches
Slide 47
Mica Black, brown, green, or violet sometimes found colorless
and shiny Breaks into smooth thin sheets Used in paints Found in
Brazil, India, US, Madagascar Crystal System: monoclinic Comes from
Latin word meanining shine Flakes sparkle in schist Very resistant
to heat and very flat Silicate
