Minerals Flashcards
what elements does hematite have?
iron & oxygen
what are the five characteristics that define a mineral
- naturally occurring or mimics nature
- Inorganic or identical to inorganic material
- Solid
- Orderly crystalline structure/chemically homogeneous
- definite chemical comp. that allows for some variation
inorganic
inorganic: found naturally in the ground and have no carbon chains attached to hydrogen
how are animals involved in the production of inorganic minerals?
what do annimals secrete (mineral) & in what forms? when is it a mineral
secrete calcite in the form of shells or coral reefs, when buried, they’re considered minerals
explain the fifth characteristic of minerals
specimen of same mineral have the same chemical formula (equal proportions of atoms), but element can substitute other elements of similar size without changing the mineral’s internal structure
5 examples of minerals containing one element and what that element is
gold (Au), diamonds (C), native copper (Cu), sulfur (S), silver (Ag)
Chemical formula of quartz, hematite, and halite
SiO2
Fe2O3
NaCl
Will specimen of the same mineral break in the same fashion?
yes
Diagnostic properties
ex. halite
aid in mineral identification (something unique about that mineral)
halite-salty
Ambiguous properties
ex.
properties that vary among specimen of the same mineral
color
what are some minerals that come in a variety of colors?
quartz
flourite
What minerals make up the rock granite?
hornblende (black)
quartz (gray)
feldspar (pink)
Luster
what are the categories
the appearance/quality of light reflected from the surface of a mineral
metallic, nonmetallic, submetallic
metallic luster
minerals that have the appearance of a metal (shiny)
examples of minerals with submetallic luster
galena and native copper: metallic but when exposed to atmosphere, they get tarnished and dull (submetallic luster)
Nonmetallic luster adjectives
vitreous (glassy), dull/earthy, pearly, silky, greasy
what mineral has a silky luster?
gypsum (satin spar)
What is the color of sulfur?
diagnostic property
hardness
yellow
rotten egg smell, softer than nail
Streak
what’s a streak plate made of?
Color of a mineral in powdered form
porcelain
why is streak useful when working with specimen? Give an example using a mineral and its luster as well (nonmetallic and metallic)
specimen of the same mineral, despite having a dif color, will have a consistent streak color
hematite comes in reddish-brown (nonmetallic) and blackish (metallic) but will both have a brick red streak
What mineral will not have a streak? Why?
quartz, harder than streak plate
What varies with specimen of the same mineral and what doesn’t?
why
physical properties change, but chemical comps don’t
ionic substitutions, impurites, defects in crystalline structure
Streak of metallic minerals vs nonmetallic
metallic: dense, dark
nonmetallic: light color
what color is pyrite
aka
brass yellow
fools gold
when do crystals develop
when in an unrestricted env
Opaque
no light transmitted
translucent
light transmitted
transparent
light and image transmitted
Crystal shape aka
definition
Habit: shape of ind. crystals or aggregates of crystals
Habit of quartz
six sided (hexagon) and pyramid-like ends
Habit of garnet, magnetite, pyrite
12-sided, octahedron, blocky
What minerals have a cube-like habit?
flourite and halite
habit adj
blocky, banded, cubic, fibrous, bladed (elongated), tabular (tablet shaped), granular (aggregates of crystals)
Hardness
what scale is used? tools associated with it and their hardness
resistance to being scratched
mohs scale
fingernail (2.5)
penny (3.5)
iron nail (4.5)
glass plate (5.5)
streak plate (6.5)
Hardness (what will be scratched, who is the scratcher?)
scratched: softer mineral
scratcher: harder mineral
Index minerals in order from soft to hard
talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, conundrum, diamond
what are hard minerals used as
2 ex
abrasives
diamonds: saws
garnets: sandpaper
what is the chemical formula for graphite? hardness compared to diamond
C, softer bc the diamond has a more compact crystal structure
what do people use to color their skin and hair? another mineral with distinctive color
hematite (red) and limonite, a variety of goethite, (yellow)
malachite (green/bluish)
cleavage
tendency of a mineral to break along planes on weak bonding (easier to break in that direction)
cleavage planes vs directions of cleavage
planes: smooth, flat surfaces
directions: cleavage suface with a different orientation
2 planes of cleavage are counted as how many directions of cleavage (parallel)
1
how do you know when a mineral demonstrates cleavage? how do you find cleavage planes?
when broken, pieces will all have the same geometry
rotate it in light
what group of minerals have 1 direction of cleavage, what’s special about them? what two minerals are a part of that group? analogy
Micas (flat sheets that can peel)
includes muscovite (lighter) and biotite (darker)
book pages can be peeled, but you can’t bend the book spine
how many directions of cleavage does halite have? Angles? habit
3 directions, 90 degrees, cubic
how many directions of cleavage does quartz have?
none, fractures into pieces that don’t resemble each other or the original crystal bc Si&O bonds are equally strong in all directions
how many directions of cleavage does olivine have?
none
how many directions of cleavage does feldspar have? angles?
2 directions, 90 degrees
how many directions of cleavage does hornblende have? angles
2 directions, 120 degrees and 60 degrees
how many directions of cleavage does calcite have? angles? shape
3 directions, 75 degrees, rhombus
how many directions of cleavage does fluorite have? galena?
4 direction
3 directions
Fracture
minerals that don’t have cleavage (chem.bonds are equally strong in all directions)
types of fractures
irregular: uneven surfaces
conchoidal: smooth, scoop curved surfaces with dangerous edges before fracture
how many cleavage surfaces does clacite have? directions?
6
3
ex of minerals w/conchoidal fracture
quartz
olivine
garnet
tenacity
adjectives
resistance to breaking, bending, deformation
brittle, malleable, sectile, elastic
minerals that are brittle
2 ex
minerals that are ionically bonded
fluorite and halite
minerals that are sectile
2 ex
minerals that can be cut into thin shavings
gypsum and talc
minerals that are elastic
micas
minerals with a high specific gravity mostly have what luster
metallic
other properties:
talc
calcite
soapy
reaction to dilute hydrochloric acid (fizzes and produce CO2) & double refraction (letters appear twice)
How to distinguish btw dif types of feldsbar?
characteristics
striations on plagioclase feldspar
potassium felspar is salmon-colored/light colored,
2 directions at 90 degrees, harder than glass
Characteristics of hematite
comes in metallic (can scratch glass) and nonmetallic (softer than fingernail) forms
red streak
Characteristics of galena
silvery metallic, very shiny
cubic/blocky cleavage
very heavy
3 directions
silver streak
characteristics of graphite
greasy
pencil lead
irregular fracture
pyroxene group
augite
amphibole group
hornsblende
talc characteristics
soapy
softer than finger
pearly
gypsum characteristics
white or translucent
1 plane of cleavage
silky
softer than a fingernail
augite vs hornblende characteristics
augite: 2 directions of cleavage at 90 degrees #13
hornsblende: 2 directions at 90 and 120 #18
both are harder than glass and greenish black to black
wha tmakes a mineral a silicate mineral
silicate anion/silicon-oxygen tetrahedron (SiO4^4-)
refractory (high melt. point and low solubility), hard to extract things from them
