Minerals! Flashcards
Quartz
SiO2
hardness: 7
streak: none
Cleavage: conchoidal
Luster: vitreous (glassy)
colorless, white, blocky
Orthoclase
(Feldspar)
Potassium rich
Hardness: 6
Fracture: 90 degree in 2 directions
Streak: White
Color: flesh pink/ off white
Plagioclase
(Feldspar)
Sodium to calcium
Hardness: 6
Streak: Colorless
colorless/white
Muscovite
Potassium
type of mica
cleavage: good in 1 direction (flexible)
Hardness: 2-2.5
color-less to light yellow
Biotite
Magnesium and Potassium
cleavage: good in 1 direction (flexible)
super flaky, thin, black/brown
Calcite
CaCO3 (calcium)
Hardness: 3
Effervescence: strong reaction
Fracture: forms rhombohedra
White to colorless
kinda looks like quartz, but a lot softer.
Dolomite
Calcium and Magnesium
Effervescence: mild reaction
Pink, flesh, white, kinda ashy
Apatite
Phosphorous
Luster: vitreous (glassy)
green!
Olivine
Magnesium
Fracture: Conchoidal
sandy olive
Hornblende
Magnesium and Calcium
Cleavage: Prismatic
Black or dark green
Serpentine
Magnesium
Luster: greasy
Variegated greens
Hematite
Iron
Streak: dusky red
Black to reddish brown color
Limonite
Iron
Streak: yellow-brown streak
dark brown to black color
Pyrite
FeS2
Hardness: 6-6.5
Streak: green to brownish black
Luster: metallic
Brass yellow color
Fool’s Gold!!
Gypsum
CaSO4
Hardness: 2 (so soft)
Luster: shiny, pearly
colorless white or grey
Luster
appearance of a mineral in reflected light
Metallic: appears as a shiny metal (pyrite(fool’s gold))
Non-metallic:
vitreous- glassy (quartz)
Pearly- iridescent (gypsum)
Greasy- oily (serpentine)
Hardness
resistance to being scratched
(harder than a pice of material if it can scratch it without being scratched)
Fingernail 2 (gypsum)
Copper penny 3 (calcite)
Steel file 5
glass 5.5
knife 6.5 (feldspars-6)
porcelain 7 (quartz)
Streak
When a mineral is scratched against an unglazed porcelain plate it leaves a streak
Hematite- burgundy
limonite- yellow brown
orthoclase- white
plagioclase- clear
minerals greater than 7 will not leave a streak (quartz)
Color
Good for identifying the key elements in dark (Fe) vs light minerals (Ca)
Some minerals have distinct colors:
Olivine- sandy olive
Apatite- green
Pyrite- metallic gold
Cleavage
A mineral with good cleavage will break along smooth surfaces
Micas- thin sheets (muscovite, biotite)
Feldspars- in two directions into rhombohedra (orthoclase, plagioclase)
Fracture
If there is no good cleavage, there will be a fracture when chipped or broken:
conchoidal- smooth, curved surfaces (quartz, obsidian)
fibrous- breaks into fibers…
uneven- rough surface with irregularities
Specific Gravity
ratio of its mass to that of equal volume of water (higher specific gravity means heavier mineral)
Effervescence
Carbonate minerals release bubbles of CO2 when reacting with HCl. It’s. diagnostic for calcite (composed of CaCO3)
Mineral
naturally occurring substance with distinct characteristics and chemical/ physical composition
