Non silicate minerals
All minerals that do not have SiO4 as their basic building blocks
Hematite
- non silicate mineral
- iron oxide
- Fe2O3 (oxidized form of iron)
Magnetite
- non silicate mineral
- iron oxide
- Fe3O4
- mixed valence in terms of iron (Fe3+, Fe3+, Fe2+)
- results in magnetism
Geothite
- FeOOH
- non silicate mineral
- iron oxide
- Fe3+
Calcite
- non silicate mineral
- classified as a carbonate mineral
- CaCO3
- different colours result from impurities
Dolomite
- non silicate mineral
- carbonate mineral
- CaMg(CO3)2
- physical properties change
Sulfide minerals
Sulphurs and a metal
Pyrite
- non silicate mineral
- sulfide mineral
- FeS2
- “fools gold” colour is diagnostic
Galena
- non silicate mineral
- sulfide mineral
- PbS
- shiny luster
Native elements
- non silicate mineral
- occurs if element itself is relatively stable and can be found in its elemental form (valence of 0)
- Gold, silver, diamond
Gypsum
- non silicate mineral
- sulphate
- CaSO4 2H20
Precipitates only in presence of water
Apatite
- non silicate mineral
- phosphate
- Ca5(PO4)3(OH, F, Cl)
most common properties used in mineral identification
- crystal form and habit
- cleavage and fracture
- luster, colour, and streak
- hardness
- other properties
Used primarily in the field
Crystal habit
Crystal shape: reflects internal crystal structure
-constant interfacial angles
-very diagnostic
E.g. quartz (hexagonal), halite (cubic)
Given time and space
- crystals can grow very large
- if space limited, minerals will interlock
Cleavage
Tendency for a mineral to break in preferred direction that follow weak atomic bonds
Cleavage surface is not the same as crystal faces
Fracture
Not the same as cleavage
Conchoidal fracturing: smooth and curved surface
Hackly fracturing: jagged and pointed surface
Uneven fracturing: irregular, rough surface
Colour, luster, and streak
Colour: not diagnostic
luster: metallic versus non metallic minerals
Streak: diagnostic colour produced by rubbing mineral on porcelain plate
Hardness
Resistance to scratching
Review chart
Other properties
- density (g/cm3) and specific gravity (weight relative to water) e.g. gold, galena
- reaction to acid (calcite reacts with 10% HCl, dolomite does not)
- taste (halite-salt)
- magnetism (magnetite is a natural magnet)
Rocks
A rock is a naturally formed, nonliving, coherent aggregate mass of solid matter that constitutes part of a planet, asteroid, moon, or other planetary object. Minerals are the most common building blocks of rocks
Three families of rocks
- Igneous: formed by cooling magma
- Sedimentary: formed from either chemical precipitation of material or deposition of transported particles
- Metamorphic: formed from changing rock as a result of either high pressures, high temperatures, or both
Best to study rocks using
Polarized light rather than ordinary because you can distinguish different minerals more easily
Magmas and igneous rocks
Composition of magma depends on what melts
Igneous rocks:
- intrusive (plutonic)
- extrusive (volcanic)
