Minerals and Rocks

S olid Cannot be a liquid or a gas N aturally Occurring Found in nature, not man-made I norganic Is not alive and never was, non-living F ixed composition Has a chemical formula, most are formed from compounds of two or more elements, some minerals consist of one element ex. Au C rystal Form A definite structure in which atoms are arranged

Is it non-living material? Is it a solid? Is it formed in nature? Does it have a crystalline structure?

Gold

Fossil

Topaz

Bones

Granite

Quartz

Pearls

Talc

Icebergs

Diamond

Coal

Rock Salt

 Minerals a) Gold b) Topaz c) Quartz d) Talc e) Iceberg* f) Diamonds  Non-Minerals a) Wood - once living b) Fossils – once living c) Bone - living material d) Granite - intrusive igneous rock e) Pearls – made by oysters f) Coal - Sedimentary rock g) Rock Salt – Sedimentary rock According to IMA – ice is listed as a mineralIMA

A mineral is a naturally formed, inorganic solid that has a definite crystalline structure.

Mineral Identification Basics PHYSICAL PROPERTIES HARDNESS HARDNESS is defined as the resistance a mineral has to being scratched - its “scratchability”. Hardness tests are done by scratching one mineral against another. The mineral that is scratched is softer than the other. Pyrite Crystals Hardness of 6.5

Mineral Identification Basics PHYSICAL PROPERTIES HARDNESS MOH’S SCALE OF MINERAL HARDNESS 1. TALC 2. GYPSUM 3. CALCITE 4. FLUORITE 5. APATITE 6. FELDSPAR 7. QUARTZ 8. TOPAZ 9. CORUNDUM 10. DIAMOND OTHER MATERIALS COMMONLY USED: FINGERNAIL 3 - COPPER PENNY GLASS STEEL FILE

Mineral Identification Basics PHYSICAL PROPERTIES CLEAVAGE CLEAVAGE is the property of a mineral that allows it to break repeatedly along smooth, flat surfaces. These GALENA cleavage fragments were produced when the crystal was hit with a hammer. Note the consistency of the 90 o angles along the edges. These are FLUORITE cleavage fragments.

Mineral Identification Basics PHYSICAL PROPERTIES CLEAVAGE Within this crystalline pattern it is easy to see how atoms will separate to produce cleavage with cubic (90 o ) angles.

Mineral Identification Basics PHYSICAL PROPERTIES CLEAVAGE These pictures show different cleavage angles and the quality of cleavage. Fluorite has cleavage in four directions A thin sheet of Muscovite seen on edge. Mica has perfect cleavage in ONE direction.

Mineral Identification Basics PHYSICAL PROPERTIES CLEAVAGE Common salt (the mineral HALITE) has very good cleavage in 3 directions. These 3 directions of cleavage are mutually perpendicular resulting in cubic cleavage.

Mineral Identification Basics PHYSICAL PROPERTIES STREAK STREAK is defined as the color of the mineral in powder form. Hematite on Streak Plate Streak is normally obtained by rubbing a mineral across a “streak plate”. This is a piece of unglazed porcelain. The streak plate has a hardness of around 7 and rough texture that allows the minerals to be abraded to a powder. This powder is the streak. Hematite has a reddish brown streak.

Mineral Identification Basics PHYSICAL PROPERTIES LUSTER LUSTER is defined as the quality of reflected light. Minerals have been grossly separated into either METALLIC or NON- METALLIC lusters. Following are some examples: Native Silver has a Metallic Luster

Mineral Identification Basics LUSTER METALLIC PHYSICAL PROPERTIES LUSTER METALLIC StibniteGalena Marcasite Pyrite

Mineral Identification Basics NON-METALLICLUSTER VITREOUS NON-METALLIC LUSTER VITREOUS Olivine - Peridot Wulfenite SpinelQuartz

Mineral Identification Basics NON METALLIC NON METALLIC LUSTER Miscellaneous Lusters Asbestos - SilkyApophyllite - Pearly Limonite - Dull or Earthy Sphalerite - Resinous Graphite has a greasy or submetallic luster and easily marks paper.

Mineral Identification Basics PHYSICAL PROPERTIES COLOR The COLOR of a mineral is usually the first thing that a person notices when observing a mineral. However, it is normally NOT the best physical property to begin the mineral identification process. Following are some examples of color variation within mineral species followed by minerals that have a distinctive color: Various colors of CALCITE.

Clear - Without Impurities Mineral Identification Basics PHYSICAL PROPERTIES COLOR Various colors of Quartz. Hematite Inclusions Chlorite inclusions Amethyst Ionic Iron

Mineral Identification Basics INDICATIVE COLOR Turquoise Sulfur Malachite Rhodochrosite Azurite

Mineral Identification Basics PHYSICAL PROPERTIES SPECIFIC GRAVITY The SPECIFIC GRAVITY of a mineral is a measure of the mineral’s density. It is related to the types of elements that make up the mineral and how they are packed into the mineral’s atomic structure. Gold in Quartz Gold has a Specific Gravity of It is 19.2 times the weight of an equal volume of water. Water has a Specific Gravity of 1.

Mineral Identification Basics PHYSICAL PROPERTIES SPECIFIC GRAVITY The SPECIFIC GRAVITY of a mineral is determined by weighing the specimen in air and then weighing it in water. It is the ratio of an object’s density to the density of water. (Weight in air) - (Weight in water ) Weight in air Specific Gravity =

Mineral Identification Basics PHYSICAL PROPERTIES TASTE IT IS NOT RECOMMENDED THAT A TASTE TEST BE PERFORMED ON MINERALS AS A STANDARD PROCESS. SOME MINERALS ARE TOXIC. However, the mineral HALITE is common salt and has a unique taste. Halite cubes from Trona, CA

Mineral Identification Basics PHYSICAL PROPERTIES MAGNETISM MAGNETISM is the ability of a mineral to be attracted by a magnet. This most commonly is associated with minerals rich in iron, usually magnetite. This is a piece of MAGNETITE with a magnet adhering to it. Magnetite is strongly magnetic in that a magnet will easily be attracted to it.

Mineral Identification Basics PHYSICAL PROPERTIES DIAPHANEITY The manner in which minerals transmit light is called DIAPHANEITY and is expressed by these terms: TRANSPARENT: A mineral is considered to be transparent if the outline of an object viewed through it is distinct. TRANSLUCENT: A mineral is considered to be translucent if it transmits light but no objects can be seen through it. OPAQUE: A mineral is considered to be opaque if, even on its thinnest edges, no light is transmitted. Quartz with Spessartine Garnets

Mineral Identification Basics PHYSICAL PROPERTIES DIAPHANEITY TRANSPARENT: A mineral is considered to be transparent if the outline of an object viewed through it is distinct. Topaz from Topaz Mountain, Utah

Mineral Identification Basics PHYSICAL PROPERTIES DIAPHANEITY Sylvite from Salton Sea, California TRANSLUCENT: A mineral is considered to be translucent if it transmits light but no objects can be seen through it. Backlit Apophyllite Crystals

Mineral Identification Basics PHYSICAL PROPERTIES DIAPHANEITY Schorl - The black variety of Tourmaline OPAQUE: A mineral is considered to be opaque if, even on its thinnest edges, no light is transmitted.

MINERAL #  Record Data