Mineral CriteriaMineral Criteria

Inorganic: not made up of living thingsInorganic: not made up of living things Naturally Occurring: exist in natureNaturally Occurring: exist in nature Crystalline Solid: regularly repeating Crystalline Solid: regularly repeating

crystalline structurecrystalline structure Consistent Chemical Composition: consistent, Consistent Chemical Composition: consistent,

no varietyno variety

Mineral ClassesMineral Classes

Silicates: contain silicon (Si) and oxygen (O)Silicates: contain silicon (Si) and oxygen (O) Nonsilicates: do not contain silicon (Si) and Nonsilicates: do not contain silicon (Si) and

oxygen (O), 6 major groupsoxygen (O), 6 major groups Carbonates, Halides, Native elements, Oxides, Carbonates, Halides, Native elements, Oxides,

Sulfates, SulfidesSulfates, Sulfides

Mineral IdentificationMineral Identification

Color: easy to observe, minerals vary in color.Color: easy to observe, minerals vary in color. Many minerals are similar in color.Many minerals are similar in color. Small amounts of certain elements may greatly Small amounts of certain elements may greatly

affect the color of a mineral.affect the color of a mineral. Weathered surfaces may hide the color of Weathered surfaces may hide the color of

minerals.minerals. Examine freshly exposed surfaces.Examine freshly exposed surfaces.

GoldGold

FluoriteFluorite

We’re going streaking!We’re going streaking!

Streak: color of the mineral in powdered Streak: color of the mineral in powdered form.form.

Rub a mineral against a piece of unglazed Rub a mineral against a piece of unglazed ceramic tile (ceramic tile (streak platestreak plate).).

The streak’s color may differ from the color of The streak’s color may differ from the color of the mineral itself.the mineral itself.

My precious, precious.My precious, precious.

Luster: light that is reflected from a mineral’s Luster: light that is reflected from a mineral’s surface.surface.

Metallic: reflects light similar to polished Metallic: reflects light similar to polished metal.metal.

Nonmetallic: All other minerals.Nonmetallic: All other minerals. Glassy, waxy, pearly, brilliant, and dull or earthy.Glassy, waxy, pearly, brilliant, and dull or earthy.

GalenaGalena

Hey, Mohs! Why I awtah…Hey, Mohs! Why I awtah…

Mohs hardness scale: standard scale against Mohs hardness scale: standard scale against which the hardness of minerals is rated. (1-10)which the hardness of minerals is rated. (1-10) 1 is soft, 10 is hard 1 is soft, 10 is hard

The bonds between the atoms that make up a The bonds between the atoms that make up a mineral’s internal structure determines the mineral’s internal structure determines the hardness of that mineral.hardness of that mineral.

Test the hardness by scratching the minerals.Test the hardness by scratching the minerals. p. 111 Mohs Hardness Scalep. 111 Mohs Hardness Scale

Hardness ScaleHardness ScaleHardness Test

1 Does not scratch your fingernail

2Scratches your fingernail, but not

penny

3 Barely scratches penny

4 Easily scratches penny

5 Barely scratches glass

6Easily scratches glass, nail can

scratch the mineral

7 Nail cannot scratch mineral

8 Scratches quartz

9 Easily scratches quartz

10 Diamond

Gypsum & TalcGypsum & Talc

DiamondDiamond

Cut!Cut!

Cleavage: tendency of a mineral to split along Cleavage: tendency of a mineral to split along specific planes of weakness to form smooth, specific planes of weakness to form smooth, flat surfaces.flat surfaces. Break along flat surfaces that generally run parallel Break along flat surfaces that generally run parallel

to planes of weakness in the crystal structure.to planes of weakness in the crystal structure.

QuartzQuartz

AcanthiteAcanthite

Time for a Break!Time for a Break!

Fracture: break unevenly into pieces that have Fracture: break unevenly into pieces that have curved or irregular surfaces.curved or irregular surfaces. Uneven or irregular fracture: rough surfaceUneven or irregular fracture: rough surface Splintery or fibrous fracture: looks like a piece of Splintery or fibrous fracture: looks like a piece of

broken wood.broken wood. Conchoidal fractures: curved surfaces.Conchoidal fractures: curved surfaces.

AsbestosAsbestos

Tiptopite (clear) MontgomeryiteTiptopite (clear) Montgomeryite

Not again!Not again!

Density: ratio of the mass to the volume of a Density: ratio of the mass to the volume of a substance. D=m/vsubstance. D=m/v Depends on the kinds of atoms that the mineral has Depends on the kinds of atoms that the mineral has

and depends on how closely the atoms are packed.and depends on how closely the atoms are packed. Heavy metals have larger densities.Heavy metals have larger densities. Helps identifying heavier minerals easier.Helps identifying heavier minerals easier.

Special PropertiesSpecial Properties

Fluorescence: glow under ultraviolet light.Fluorescence: glow under ultraviolet light. Phosphorescence: continue to glow after Phosphorescence: continue to glow after

ultraviolet light is removed.ultraviolet light is removed. Magnetism: attract metal, contain iron.Magnetism: attract metal, contain iron. Radioactivity: nuclei of some atoms are Radioactivity: nuclei of some atoms are

unstable.unstable. Results in nuclei decay over time.Results in nuclei decay over time.

MagnetiteMagnetite

Lights, Camera, Action!Lights, Camera, Action!

Light rays bend as they pass through Light rays bend as they pass through transparent minerals.transparent minerals.

Double Refraction: Light rays are split into 2 Double Refraction: Light rays are split into 2 parts as they enter the crystal.parts as they enter the crystal. Produces a double image.Produces a double image.