1. Minerals What are minerals and how do we classify them?

2. Minerals Minerals are the ingredients needed to form the different types of rocks Rock – is any naturally formed solid that is part of Earth or any other celestial object

3. Minerals Mineral – naturally occurring, inorganic solid with a definite structure and composition, where atoms are arranged in a repeating pattern Inorganic – not made by or composed of living things Crystalline – a solid in which the atoms are arranged in a repeating pattern

4. Minerals Minerals form by three methods: 1.Crystallization – a process of organizing atoms to form crystalline solids 2.Recrystallization – the cooling and hardening of lava or magma into mineral 3.Rearrangement – the realignment of atoms in minerals under high temperature and pressure

5. Minerals Most rock forming minerals are silicates that result in a tetrahedron shape Four-sided units of 4 oxygens and 1 silicon

6. Minerals Crystal structure or “internal arrangement of atoms” are responsible for the physical and chemical properties that a mineral has

8. Minerals Each mineral has a set of physical and chemical properties that can be used to identify the sample The methods we use to classify minerals are:

9. Minerals Color Color – a visual characteristic of an object One of the most obvious, but not the most reliable Many of the 4000 known minerals share similar colors

10. Minerals

11. Streak Streak – the color of finely crushed powder when a mineral is dragged across a streak plate Weathering changes the outside color, but streak gives the true color

12. Minerals Luster Luster – the shine of an unweathered mineral or the way it looks in reflected light Two types of luster: 1.Metallic luster – shines like stainless steel 2.Nonmetallic luster – earthy, waxy, pearly or dull

13. Minerals

15. Density Density – the ratio of mass and volume of an object

16. Minerals Density Sample Problem: a student measures the mass of a mineral to be 350g and calculates the volume to be 35mL. What is the density? D=M/V 350g 35mL = 10g/mL

17. Minerals Hardness Hardness – resistance of a mineral to be scratched Mohs Hardness Scale is used to classify hardness

18. Minerals Hardness Determination Rather than carry samples of the ten standard minerals, a geologist doing field work usually relies on common objects to test for hardness (fingernail, copper penny, steel nail or knife blade, glass plate).

19. Minerals HardnessMineralTest 1TalcFinger nail scratches easily 2GypsumFinger nail scratches 3CalciteCopper penny scratches 4FlouriteSteel knife scratches easily 5ApatiteSteel knife scratches 6FeldsparSteel knife will not scratch 7QuartzWill scratch glass and steel 8TopazHarder than any common mineral 9CorundumScratches topaz 10DiamondHardest mineral

20. Minerals Cleavage Cleavage – the tendency of a mineral to break along zones of weakness and form semi-smooth or parallel surfaces

21. Minerals

23. Fracture Fracture – an irregular or uneven break Tends to not have zones of weakness

24. Minerals

25. Acid Test Acid Test – when dilute acid (HCl) is placed on a mineral it can bubble Calcite and Dolomite both react with acid

26. Reaction to Acid

27. Minerals Other Properties

28. Minerals Double Refraction Double refraction - Light is separated into two rays producing a double image. Clear calcite (the variety known as Iceland Spar ) displays excellent double refraction.

29. Minerals Magnetism Magnetism – when a mineral is attracted to metal

30. Minerals Mineral Identification Observe the various physical properties. Refer to identification flow charts to determine the mineral name of the sample.

32. Minerals ESRT p.16