Day 2 Mineralogy Flashcards
What are the three major carbonate groups?
Calcite group, Aragonite group, Dolomite group
One of the most common rock-forming minerals, its crystals are extremely varied in habit and often complex. Important habits are prismatic, rhombohedral, and scalenohedral. Usually in crystals or in coarse- to fine-grained aggregates, and has rhombohedral perfect cleavage.
Calcite
The chemically pure and optically colorless variety of calcite
Iceland spar
Cellular deposits formed around hot or cold calcareous springs are known as?
travertine or tufa
Calcite is a late crystallization product in the cavities of lavas and is also a common mineral in hydrothermal veins associated with ____________
sulfide ores
Calcite may also be a primary mineral in some igneous rocks such as ____________ and ____________
carbonatites and nepheline syenite
Common as stalagmites, stalactites, and incrustations in cave deposits
Calcite
How is calcite distinguished from dolomite?
coarse fragments of calcite effervesce freely in cold dilute HCl
How is calcite distinguished from aragonite?
lower specific gravity and rhombohedral cleavage
Common in veins and irregular masses derived from the alteration of Mg-rich metamorphic and igneous rocks, and is a constituent of serpentinites and altered peridotites.
Magnesite
Magnesite that are a constituent of serpentinite is compact and cryptocrystalline and may be associated with ___________
opaline silica
This magnesite is found in talc, chlorite, and mica schists and in dolomitic limestones.
Cleavable magnesite
The white massive variety of magnesite resembles chert. How is magnesite distinguished from chert?
Magnesite has a lower degree of hardness (vs Chert)
How are cleavable magnesites are distinguished from dolomite?
by higher specific gravity
True or False: Magnesite dissolves in cold HCl.
False. Magnesite is almost nonreactive in cold HCl, but dissolves with effervescence in hot HCl.
As a vein mineral, in well-crystallized form, it is associated with metallic ores containing silver minerals, pyrite, chalcopyrite, and galena.
Siderite
Siderite with admixed clay minerals, in concretions with concentric layers
clay ironstone
Siderite found in shales and coal, contaminated with carbonaceous material.
blackband ore
Siderite is a common constituent of _________________, in association with chert and magnetite.
sedimentary Precambrian iron-formations
What causes the brownish color of siderite?
presence of iron
What distinguishes siderite from other carbonates?
Its brownish color and high specific gravity
How is siderite distinguished from sphalerite?
by its rhombohedral cleavage
True or False: Siderite is soluble as fragments in cold HCl.
False. Siderite is soluble in powdered form in cold HCI, and as fragments in hot HCI with effervescence.
A constituent of hydrothermal veins with ore minerals of silver, lead, and copper, and of manganese deposits.
Rhodochrosite
What are the two diagnostic characteristics of rhodochrosite?
Its pink color and rhombohedral cleavage
What distinguishes rhodochrosite from rhodonite?
Hardness. Rhodochrosite has a hardness of 4, while Rhodonite has 6.
True or False: Rhodochrosite is not soluble in HCl.
False. Rhodochrosite is soluble in hot HCI with effervescence
Usually reniform, botryoidal, or stalactitic, and is often dirty brown in color.
Smithsonite
The yellow smithsonite variety
turkey-fat ore
Mineral of supergene origin, usually found with zinc deposits in limestones, and associated with sphalerite, galena, hemimorphite, cerussite, calcite, and limonite.
Smithsonite
True or False: Smithsonite effervesces in powdered form and in cold HCl.
False. Smithsonite effervesces in powdered form and in hot HCI.
The orthorhombic polymorph of calcite, deposited from hot springs, and associated with gypsum.
Aragonite
Aragonite occurs as __________ on serpentine and in ___________ in basalt.
fibrous crusts; amygdaloidal cavities
As a result of crystallization at high pressure but relatively low temperature, aragonite occurs in metamorphic assemblages of which facies?
blueschist facies
The pearly layer of many shells and the pearl itself is what mineral?
Aragonite
Columnar aragonite has cleavage parallel to ____________
elongation
How is aragonite distinguished from witherite and strontianite?
by lower specific gravity and lack of distinctive flame coloration.
True or False: Aragonite does not effervesce in HCl.
False. Aragonite effervesces in cold, dilute HCl
In hydrothermal veins associated with galena.
Witherite
A sulfate mineral that occurs most commonly in hydrothermal veins associated with ores of silver, lead, copper, cobalt, and manganese.
Barite
Chemical formula of Barite
BaSO4
A sulfate mineral that is recognized by its high specific gravity, characteristic cleavage, and crystal form. Gives a yellowish-green flame test.
Barite
(Sulfate) Orthorhombic crystals closely resemble those of barite. Commonly tabular on {001} or prismatic parallel to the a or b axis. Also radiating fibrous; granular.
Celestite
Chemical formula for Celestite
SrSO4
T or F. Celestite occurs most commonly as disseminations through limestone or sandstone, or in nests and lining cavities in such rocks.
T
How is celestite differentiated from barite?
lower specific gravity and a crimson flame test (for Sr)
What are the characteristic habits of some celestite?
Fine radiating or fibrous habit
What is the usual color of celestite?
Pale blue
Chemical formula for Anglesite
PbSO4
Closely resembles barite but is differentiated by lower specific gravity and a crimson flame test (for Sr).
Celestite
Sulfate mineral which is adamantine when crystalline, dull when earthy
Anglesite
Anglesite is frequently earthy, in concentric layers that may have an unaltered core of what mineral
Galena
(Sulfate) A common supergene mineral found in the oxidized portions of lead deposits. Associated with galena, cerussite, sphalerite, smithsonite, hemimorphite, and iron oxides.
Anglesite
Anglesite may become dark gray. What causes this?
Impurities
A sulfate mineral that is recognized by its high specific gravity, its adamantine luster, and its common association with galena.
Anglesite
A common supergene mineral found in the oxidized portions of lead deposits. Associated with galena, cerussite, sphalerite, smithsonite, hemimorphite, and iron oxides.
Anglesite
Chemical formula of Anglesite
PbSO4
What makes anglesite recognized from other minerals?
high specific gravity, adamantine luster, and its common association with galena
Which sulfate mineral has the highest specific gravity and why?
Anglesite; because of the presence of lead
SG= 6.2-6.4
This mineral has a usually massive or in crystalline masses resembling an isometric mineral with cubic cleavage; it has three pinacoidal cleavages
Anhydrite
What is the chemical formula for Anhydrite
CaSO4
Anhydrite is found in the same manner, but less commonly- occurring as
Gypsum
What is the usual color of anhydrite?
colorless to bluish or violet
Occurs in beds associated with salt deposits in the cap rock of salt domes, and in limestones; also in amygdaloidal cavities in basalts
Anhydrite
T or F. Anhydrite s found in much the same manner as gypsum, with which it is commonly associated, but is more abundant than gypsum
F. less common
How is anhydrite distinguished from calcite?
higher specific gravity
How is anhydrite distinguished from gypsum?
greater hardness (anhydrite) and water content (of gypsum)
Characterized by its three cleavages at right angles. It is distinguished from calcite by its higher specific gravity and from gypsum by its greater hardness.
Anhydrite
Commonly tabular on {010}; diamond-shaped with beveled edges. Twinning on {100} common, resulting in swallowtail twins; Commonly distributed in sedimentary rocks, often as thick beds.
Gypsum
What will happen if you hydrate your anhydrite?
It will turn to gypsum
What is the chemical formula for gypsum
CaSO4·2H2O
A fibrous gypsum with silky luster
Satin spar
Fine-grained massive variety of gypsum
Alabaster
A gypsum variety that yields broad, colorless, and transparent cleavage folia.
Selenite
Gypsum is frequently formed by the alternation of?
Anhydrite
Gypsum is found as a __________ mineral in metallic veins
gangue
______ is a gypsum variety that yields broad, colorless, and transparent cleavage folia.
Selenite
T or F. Gypsum is commonly distributed in metamorphic rocks, often as thick beds
F. Gypsum is commonly distributed in sedimentary rocks, often as thick beds
Chemical formula of gypsum
CaSO4·2H2O
Usually as rhombohedra, often with curved faces, and when strongly curved known as “saddle-shaped” crystals
Dolomite
Generally not found in well-formed crystals; When in crystals, they resemble those of dolomite.
Ankerite
Ankerite is typically yellowish white. What causes it to become yellowish brown?
Oxidation (due to some of the iron)
Occurrence of dolomite is most common in sedimentary rocks as
dolomite or dolostone
A tungstate mineral recognized by its high specific gravity, crystal form, fluorescence in shortwave ultraviolet light, and generally light color.
Scheelite
Most scheelite will fluoresce with ________ color in short ultraviolet radiation.
bluish-white
What type of marble does dolomite occur as?
Dolomitic marble
Found in granite pegmatites, contact metamorphic deposits, and high-temperature hydrothermal veins associated with granitic rocks.
Scheelite
Ankerite is a common carbonate in Precambrian iron-formations in association with?
chert, magnetite, and hematite
Scheelite is commonly associated with these minerals
cassiterite, topaz, fluorite, apatite, and molybdenite
Dolomite occurs as a hydrothermal vein mineral, especially in________ and ________ veins that traverse limestone, associated with fluorite, calcite, barite, and siderite.
lead, zinc
SG and hardness of Scheelite
SG= 5.9-6.1
hardness = 4.5-5
Chemical formula for scheelite
CaWO4
Name 3 phosphates
Apatite, Amblygonite, Turquoise
Phosphate materials of _______ and ______ are members of the apatite group
bones and teeth
(phosphate) Can be scratched by knife
Apatite (hardness= 5); knife= 5.5
The variety __________ (a massive, cryptocrystalline type) constitutes the bulk of phosphorite or phosphate rock
collophane
Usually recognized by a combination of its color, hexagonal crystal form, and hardness. It is distinguished from beryl by inferior hardness and from quartz by color and hardness
Apatite
Chemical formula of apatite
CaAl5(PO4)3(F, Cl, OH)
Found mainly in Li-bearing granite pegmatites in association with spodumene, tourmaline, lepidolite, and apatite
Amblygonite
In a flame test, amblygonite will give ______________ color due to presence of ____ element
diagnostic red; Li
Hardness of Amblygonite
6
chemical formula of amblygonite
LiAl(PO4)(F, OH)
This phosphate mineral transmit light on thin edges
Turquoise
Dolomite and ankerite have similar properties except for the color differences. Dolomite has color variations of colorless, white, gray, green, or some shade of light pink, or flesh color, while Ankerite has the color variations of ___________.
yellowish white to yellowish brown
A secondary mineral found in small veins and stringers traversing more or less decomposed volcanic rocks in arid regions.
Turquoise
Turquoise is easily recognized by its color. It is harder than ________, the only common mineral that it resembles
chrysocolla
Turquoise has a _________ luster
wax-like
Cuprite occurs as ruby red in transparent crystals, and it is called
Ruby copper
Usually distinguished by its red color, isometric crystal form, high luster, brown, streak, and association with limonite.
Cuprite
Chemical formula of cuprite
Cu2O
Characterized chiefly by its great hardness, high luster, specific gravity, and parting. It may display hexagonal dipyramids that are rounded into barrel shapes with deep horizontal striations.
Corundum
Chemical formula of corundum
Al2O3
Hardness of Corundum
9
Corundum also occurs as __________ in detrital soil and stream sands.
rolled pebbles
Distinguished mainly by its characteristic red streak, reddish-brown to black color, and earthy to metallic luster. It is the most abundant iron ore mineral in Precambrian banded iron-formations.
Hematite
Chemical formula of hematite
Fe2O3
Red earthy variety of hematite
Red ocher
Platy and metallic variety of hematite
Specularite
Micaceous and foliated hematite
Specular hematite
Hematite with botryoidal to reniform shapes with radiating structures
Kidney ore
How is ilmenite distinguished from hematite?
streak
How is ilmenite distinguished from magnetite?
lack of strong magnetism
A common accessory in igneous rocks. May occur as large masses in gabbros, diorites, and anorthosites, commonly associated with magnetite. Most commonly massive and compact, also in grains or as sand.
Ilmenite
Chemical formula of ilmenite
FeTiO3
Characterized by its adamantine luster and red color. Usually subtranslucent, may be transparent. Commonly in tetragonal, prismatic crystals with dipyramid terminations and vertically striated prism faces. Frequently in elbow twins. Habit of crystals may be slender acicular.
Rutile
Chemical formula of rutile
TiO2
How is rutile distinguished from cassiterite?
Lower specific gravity
Rutile may be included in which two minerals as a fine-grained slender crystals?
Quartz and Mica
Usually in radiating fibers or columns. Also granular massive; often in reniform coats and dendritic shapes finely overgrown with other Mn-oxides and hydroxides. Frequently pseudomorphous after manganite. Iron black streak.
Pyrolusite
Chemical formula of pyrolusite
MnO2
Coarsely crystalline pyrolusite has a hardness of 6-6.5. What is this variation called?
Polianite
It is found as nodular deposits in bogs, on lake bottoms, and on the floors of oceans. Also occurs in veins associated with quartz and various metallic minerals. It is the most common manganese ore mineral and is widespread in its occurrence.
Pyrolusite
Recognized by its high specific gravity, adamantine luster, and light streak. Present as an accessory mineral of igneous rocks and pegmatites, but most commonly found in high-temperature hydrothermal veins in or near granitic rocks.
Cassiterite
Chemical formula of cassiterite
SnO2
Cassiterite in reniform shapes with radiating fibrous appearance is called?
Wood tin
Cassiterite variation that may also occur as rolled pebbles in placer deposits
Stream tin
Characterized chiefly by its pitchy luster, high specific gravity, color, streak, and strong radioactivity (as detected by a Geiger counter or scintillation counter).
Uraninite
Most commonly as massive or botryoidal forms with a banded structure variation of Uraninite
Pitchblende
Chemical formula of uraninite
UO2
Isometric. Recognized by its hardness, octahedral crystal form, and vitreous luster. Common in twinned octahedrons. Dodecahedron may be present as small truncations but other forms are rare. Also massive and in irregular grains.
Spinel
The metamorphic assemblages of spinel may contain
phlogopite, pyrrhotite, and graphite
Chemical formula of spinel
MgAl2O4
Isometric. Frequently in octahedral crystals, more rarely in dodecahedrons. Other forms rare. Usually granular massive, coarse- or fine-grained. Characterized by its strong magnetism, black color, and hardness of 6.
Magnetite
Chemical formula of magnetite
Fe3O4
Magnetite may act as a natural magnet, and it is known as
Lodestone
Magnetite is often closely intergrown with corundum, forming ___________.
Emery
Isometric, with octahedral habit, but crystals rare. Commonly massive, granular to compact. Association with olivine and serpentine is highly characteristic.
Chromite
How is chromite distinguished from magnetite?
Lack of magnetism and brown streak
Chemical formula of chromite
FeCr2O4
Recognized by its foliated nature, light color, and pearly luster on cleavage faces. Found in association with serpentine dolomite, magnetite, and chromite. As a reaction product of Mg-silicates, especially serpentine. Basal {0001} perfect. Folia flexible but not elastic. Sectile.
Brucite
Chemical formula of brucite
Mg(OH)2
How is brucite distinguished from talc?
by being considerably harder
How is brucite distinguished from mica?
by being inelastic
Its black color and prismatic crystals are most diagnostic. Monoclinic crystals that are prismatic parallel to the c axis and vertically striated. Often columnar to coarse – fibrous. Contact and penetration twins common.
Manganite
Chemical formula of manganite
MnO(OH)
How is manganite distinguished from pyrolusite?
Hardness (4) and brown streak
A product of secondary alteration of original Mn-carbonates, Mn-silicates, or both. Generally in association with pyrolusite in manganese ore deposits, in nodular deposits in bogs, and on lake bottoms and on see and ocean floors. Massive, botryoidal, stalactitic; appears amorphous.
Romanechite
How is romanechite distinguished from other oxide minerals?
its greater hardness (5-6) and botryoidal form
How is romanechite distinguished from limonite?
by its black streak
Many of the hard botryoidal masses formerly called _____________ are mixtures of manganese oxides of which romanechite is a major constituent.
psilomelane
Rarely in distinct prismatic (orthorhombic), vertically striated crystals. Generally massive, reniform, stalactitic, and in radiating fibrous aggregation. Foliated. A common mineral resulting from oxidation and weathering of iron-bearing minerals.
Goethite
Chemical formula of goethite
FeO(OH)
Generally loose and porous variation of goethite
Bog ore
Goethite constitutes the gossan or ___________ over metalliferous vein deposits.
iron hat
How is goethite distinguished from colloform hematite and romanechite?
by color and streak
A field term used for very fine-grained to amorphous mixtures of brown ferric hydroxides whose real identities are unknown.
Limonite
Chemical formula of limonite
FeO(OH)·nH2O
Limonite has variable compositions and consists of a mixture of several iron hydroxides or of a mixture of several minerals such as hematite, goethite, or lepidochrocite, with or without additional ____________.
absorbed water
Native mineral with crystal form commonly in irregular plates, scales, or masses. Also in rounded or flattened grains “nuggets”
Gold
True or False: Bauxite is a mineral term.
False. Bauxite is a rock term.
Bauxite consists of a very fine-grained intergrowth of three aluminum hydroxides namely:
diaspore, gibbsite, and boehmite
T or F. Gold is very malleable and sectile. It fractures hackly
T
Bauxite is the major ore of __________.
Aluminum
Formed in the tropics, __________ is a soil consisting mainly of hydrous aluminum and ferric oxides.
Laterite
Gold is usually in various shades of yellow depending on purity, becoming paler with increasing ______ content
silver
Recognized by its light, commonly yellowish-brown color, pisolitic and earthy texture, and low degree of hardness.
Bauxite
Name the 2 chief sources of gold
Hydrothermal gold - presence of gold cannot be detected with the eye
Placer deposits - gold occurs as fine detrital grains and nuggets
How to distinguish gold from pyrite and chalcopyrite?
Pyrite- much greater hardness
Chalcopyrite - is brittle instead of malleable and sectile
A term used to describe crystal shapes when the faces of the cube have grown more at the edges than in the center.
hopper-shaped
Specific gravity of gold when pure
19.3
Characterized by its cubic cleavage and salty taste. Occurs most commonly in evaporite deposits, associated with gypsum, anhydrite, dolomite, and shale.
Halite
Chemical composition of halite
NaCl
T or F. Presence of other metals increases the specific gravity of Gold.
F. Presence of other metals (usually silver) decreases the specific gravity of Gold, which may be as low as 15
Valuable deposits are also found in intrusive masses known as ___________, which have their roots in thick, bedded deposits.
salt domes
When in crystals or granular crystalline masses showing cubic cleavage, it is known as
Rock salt
How is halite distinguished to sylvite?
by a less bitter taste and yellow flame color
A native element with isometric crystal commonly malformed and branching, arborescent, or reticulated groups. Also in coarse or fine wire. Usually in irregular masses, plates, and scales
Silver
Has the same origin, mode of occurrence, and associations as halite but is much rarer. Colorless to white; also shades of blue, yellow, or red caused by impurities. Transparent when pure.
Sylvite
Chemical formula of sylvite
KCl
Silver has SG of 2.5-3. Malleable and _________
ductile
What causes the yellow flame color of halite?
Presence of sodium
Give the SG of silver when pure and when impure
pure = 10.5
impure = 10-12
Silver turns to what color when tarnished?
brown or gray-black
Isometric, usually in cubes, and often in penetration twins. Other crystal forms are rare. Distinguished by its cubic crystals and perfect octahedral cleavage. Also by its vitreous luster and usually fine coloring, and by the fact that it can be scratched by a knife.
Fluorite
Chemical formula of fluorite
CaF2
Native silver in large deposits has been precipitated from ___________
primarily hydrothermal solutions
Fluorite may be the ________ mineral in hydrothermal veins, and _______ mineral in metallic ores.
chief; gangue
How is fluorite distinguished from calcite?
It is harder than calcite and does not effervesce with cold HCl.
A native element which is usually in irregular masses, plates, and scales, and twisted and wirelike forms
Copper
Copper is _________ on fresh surface, usually dark with dull luster because of ________
copper red; tarnish
Primary deposits of native copper are associated with basaltic lavas, where copper was deposited through the reaction of ___________ with ___________ minerals.
hydrothermal solutions; iron-oxide
SG of native copper
8.9
A native mineral with massive crystal habit, reniform, stalactitic, as incrustations, earthy.
Sulfur
It is found near the crater rims of active or extinct volcanoes, deposited from volcanic gases. It also occurs in veins with the metallic sulfides formed by the oxidation of the sulfides
sulfur
T or F. Sulfur is a good conductor of heat.
F. poor conductor
What happens to sulfur crystal when held close to the ear?
You will hear it crack.
How to distinguish sulfur from orpiment?
sulfur = absence of cleavage
______ is a variety of diamond, has rounded forms and a rough exterior resulting from a radial or cryptocrystalline aggregate. The term is also applied to badly colored or flawed diamonds without gem value
Bort
Hardest known mineral
Diamond
_______________ is a black or grayish-black bort. It is noncleavable, opaque and less brittle than crystals
Carbonado/carbon
The primary occurrence of diamonds is in altered peridotite called ______________, as intrusive bodies that are commonly circular with pipelike shape and referred to as “diamond pipes”
kimberlite
A large percentage of the diamonds are recovered from alluvial deposit known as _______
placers
synthetic diamonds are called
cubic zirconia
1 carat of diamond is equivalent to how many milligrams?
200 mg
A native element with characteristic “greasy feel”
graphite
T or F. Graphite occurs commonly in metamorphic rocks such as crystalline limestones, schists, and gneisses.
T
Distinguishing properties of graphite from molybdenite
graphite= black color; black streak
molybdenite= blue tone; grayish-black streak
Sulfide mineral the most commonly have massive and very fine-grained crystal form. This is one of the most important copper ore minerals.
Chalcocite
Chalcocite is usually shinning lead gray, tarnished to dull black upon ___________
exposure
Chalcocite is also a constituent of “_________________” deposits disseminated throughout porphyritic granodiorite intrusives
porphyry copper
Chemical formula of chalcocite
Cu2S
A usually massive sulfide which occurs less frequently as supergene mineral in the upper enriched parts of the copper veins.
bornite
It is distinguished by its characteristic brown color on the fresh fracture and the purple tarnish
bornite
Bornite is also known as _____________
peacock ore
chemical formula for bornite
Cu5FeS4
A very common metallic sulfide mineral is recognized by its good cubic cleavage, high specific gravity, softness, lead-gray color and streak. It is found in veins associated with sphalerite, marcasite, chalcopyrite, etc.
Galena
SG of Galena
7.4-7.6
Why do galena have relatively high SG compared to other sulfides?
Due to the presence of Pb
Chemical formula of Galena
PbS
Isometric sulfide mineral with tetrahedron, dodecahedron, and cube as common forms. Is the common ore mineral for zinc.
Sphalerite
Sphalerite is ________ when pure and _____________ when nearly so.
colorless; green
Sphalerite has _________ luster and ______________ streak
resinous; white to yellow and brown
Chemical formula for Sphalerite
ZnS
