Quiz 3 Flashcards
Epidote
Sorosilicates
**Ca, Al, Fe, Si
Ca2(Al,Fe)2(SiO4)3(OH)
SF: Greenish color and common crystal habits
Envi: meta; hornfels, skarns, meta limestones, schists; ig; basalt, granite peg
IG, SED, META
H: 6-7 C: 1,1 F: uneven L: vitreous Cr Habits: long, slender crystals;
Clinozoisite
Sorosilicates
**Ca, Al, some iron
Ca2Al2(Al, Fe3+)OOH
SF: color, cleavage, envi
Envi: contact meta; hornfels, skarns, meta limestones
META
H: 7 C: 1,1 F: uneven L: vitreous Cr Habits: prismatic, elongated crystals;
Beryl
Ring Silicates/Cyclosilicates
Be3Al2SiO6
SF: crystal form, hardness
Envi: ig; granite peg, rhyolite deposits; meta; mica schists
H: 7.5-8 C: 3,1; basal F: uneven to conchoidal L: vitreous, waxy Cr Habits: hexagons,
Tourmaline (schorl, elbaite, dravite)
Ring Silicates/Cyclosilicates
Tourmaline: B
Schorl: Fe
Elbite: Li
Dravite: Mg
SF: color, crystal form, hardness, deep vertical striations
Envi: schorl, elbaite = granite peg; dravite = meta
IG, META
H: 7-7.5 C: 3,2 F: conchoidal to uneven L: vitreous; black and brown may be dull Cr Habits: elongated or stubby, prismatic crystals, striated; rounded triangular cross section
Augite
(Ca,Na)(Mg,Fe,Al)(Al,Si)2O6
SF: Color, crystal habits, cleavage, and environment
Envi: ig; basalt, diabase, gabbro, peg; meta; serpentine deposits
IG, META
H: 5-6 C: 1,2; may have parting F: uneven to splintery L: vitreous, dull Cr Habits:
Diopside
CaMgSi2O6
SF: color, cleavage angles
Envi: contact/regional meta; hornfels and skarn hydroT deposits
META
H: 5-6 C: 1,2; may have parting F: vitreous to dull L: uneven, splintery Cr Habits:
Spodumene
LiAlSi2O6
SF: Distinct crystal habit, cleavage angles, and hardness
Envi: ig; lithium bearing peg
IG
H: 6.5-7 C: 1,2 F: uneven, splintery L: vitreous, silky Cr Habits: most often as long, flat, prismatic crystals; rectangular crystals, tabular, bladed, as elongated crystals
Wollastonite
CaSiO3
SF: Cleavage angle, crystal habit,
Envi: meta; hornfels and marbles
META
H: 4.5-5 C: 1,2 F: uneven, splintery L: vitreous to silky Cr Habits: rarely single crystals; often twinned; usually fibrous, radiating, grainy, bladed, massive, as cleavage fragments, and as compact groupings of elongated tabular crystals
Pectolite
NaCa2Si3O8(OH)
SF: Crystal habits and mineral associations
Envi: usually ig; veins of basalt/diabase; meta serpentine deposits
IG, META
H: 4.5-5 C: 2,2; forms at angle near 90 degrees F: splintery; uneven L: vitreous, splintery Cr Habits: single crystals are very rare; fibrous, radiating veins;
Hornblende
Mg, Fe2+, Fe3+, Al
SF: Color, crystal aggregates, and cleavage angle of amphibles
Envi: rock forming material;
IG, META
H: 5-6 C: 2,2; prismatic F: uneven, splintery L: vitreous, submetallic, dull Cr Habits: prismatic or tabular crystals with a diamond-shaped cross-section; not usually single crystals
Tremolite - Actinoite
Ca2(Mg,Fe)5Si8O22(OH)2
SF: crystal habit and cleavage angle of amphiboles
Envi: contact meta; hornfels and skarns, serpentine deposits; meta calcite and dolomite; secondary min in ig basalt and diabase
IG, META
H: 5-6 C: 2,2; prismatic F: uneven, splintery L: vitreous, silky Cr Habits: elongated prismatic crystals; bladed groups; fibrous;
Kaolinite
Al2Si2O5(OH)4
SF: friable habit and clay-like texture
Envi: secondary altering min in weathering; ig, sed, meta; near oxidized surface where altered form Al silicates like feldspars
IG, SED, META
H: 2-2.5 C: 1,1 F: earthy L: dull Cr Habits: most often as unshaped compact masses; tiny grains and plates; crystals rarely visible to naked eye
Glauconite
(K,Na)(Fe+++,Al,Mg)2(Si,Al)4O10(OH)2
SF:
Envi:
H: 2 C: perfect F: earthy L: dull Cr Habits: Micaceous - Platy texture with "flexible" plates
Talc
Mg3Si4O10(OH)2
SF: soft, greasy feel
Envi: meta; serpentine deposits
META
H: 1 C: 1,1 F: uneven L: greasy, waxy, pearly Cr Habits: large distorted masses and foliated sheets and plates, micaceous, radiating, botryoidal, and in fibrous masses
Muscovite
KAl3Si3O10(OH)2
SF: flaky habit, crystals, sectility, and mode of occurence
Envi: ig; granite peg; meta; contact, schists, hydroT veins
IG, META
H: 2-2.5 C: 1,1 F: uneven L: pearly; flaky, submetallic Cr Habits: thick flakes, micaceous masses, tabular, foliated, flaky, and scaly forms
Biotite
K(Mg,Fe2+3)(Al,Fe3+)Si3O10(OH,F)2
SF: flaky habit, crystals, sectility, and mode of occurence
Envi: meta; schists and gneiss; ig; granites, rhyolites, primary mica in rare earth pegmatites
IG, META
H: 2.5-3 C: 1,1 F: uneven L: pearly, submetallic Cr Habits: thick flakes, micaceous masses, tabular, foliated, flaky, and scaly forms
Lepidolite
K(Li,Al)3(Si,Al)4O10(F,OH)2
SF: flaky habit, crystals, color, sectility, and mode of occurence
Envi: ig; high-lithium granite pegmatites
IG
H: 2.5-3 C: 1,1 F: uneven L: pearly Cr Habits: small, scaly crystals in dense aggregates, micaceous masses and groupings, and in tabular, foliated, flaky, and scaly forms
Serpentine
Mg3Si2O5(OH)4
or X2-3Si2O5(OH)4
SF: greasy feel, soft, and may be flexible and elastic
Envi: rock forming mineral in metamorphic
META
H: 2-5
C: usually not discernible because of crystal development
F: conchoidal, splintery
L: greasy, waxy, or silky
Cr Habits: massive, platy, fibrous (forming tough, flexible and elastic fibers), botryoidal, columnar, earthy, platy, micaceous, in pyramidal groupings, in parallel bladed groups, and as fibrous veins
Quartz
SiO2
SF: hardness, crystal forms, striations on crystal faces, and frequent appearance of conchoidal fractures on crystal faces
Envi: all mineral environments
IG, SED, META
H: 7 C: - F: conchoidal L: vitreous Cr Habits:
Orthoclase
KAlSi3O8
SF: crystal habits, cleavage, and hardness
Envi: low temp meta rocks; ig; peg, sed; conglomerates
IG, SED, META
H: 6
C: 2,1 - basal ; 2,1 - prismatic ; 3,1 - pinacoidal. The cleavage angle is about 90º
F: conchoidal to uneven
L: vitreous, pearly
Cr Habits: well shaped prismatic and tabular crystals, which are sometimes striated; penetration and repeated twins
Microcline
KAlSi3O8
SF: crystal habits, cleavage, and hardness
Envi: ig; peg, meta; hydroT veins, sed; conglomerates
IG, SED, META
H: 6
C: 2,1 - basal ; 2,1 - prismatic ; 3,1 - pinacoidal. The cleavage angle is about 90º
F: conchoidal to uneven
L: vitreous
Cr Habits: well formed crystals, similar to orthoclase (twinning habits), grainy and in compact crystal aggregates
Plagioclase
(Na,Ca)Al1-2Si3-2O8
SF: crystal habits, cleavage, and hardness
Envi: commonly clast produced during the weathering of ig and meta rocks
IG, SED, META
H: 6-6.5
C: 2,1 - basal ; 2,1 - prismatic ; 3,1 - pinacoidal. The cleavage angle is about 90º
F: conchoidal to uneven
L: vitreous; pearly on cleavages
Cr Habits: flat and bladed, compact groupings, tall prismatic and short, stubby, tabular crystals, grainy; striated often
Nepheline
(Na,K)AlSiO4
SF: environment, greasy luster, and cleavage
Envi: alkaline igneous nepheline syenites and nepheline syenite pegmatites
IG
H: 5.5-6 C: 2,3 F: subconchoidal to uneven L: vitreous to greasy Cr Habits: good hexagonal shape, inter grown/stacked crystals, massive or grainy
