What is a Mineral What is a mineral

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What is a Mineral?

What is a Mineral?

What is a mineral? o Elements which can be described in chemical terms or

What is a mineral? o Elements which can be described in chemical terms or compounds composed of two or more elements and found occurring naturally in the Earth are termed minerals.

Some general facts: o Over 2, 000 minerals have been identified. o Elements combine

Some general facts: o Over 2, 000 minerals have been identified. o Elements combine to form minerals. o Some minerals are “native elements. ” That means they are made of only one element, like gold, copper, and sulfur.

Native Elements Gold Sulfur

Native Elements Gold Sulfur

How do we identify minerals? o Physical Properties o Chemical Properties

How do we identify minerals? o Physical Properties o Chemical Properties

How do we identify minerals? Physical o Crystal Form o Crystal form indicates the

How do we identify minerals? Physical o Crystal Form o Crystal form indicates the internal molecular arrangement of the mineral o There are six forms o o o Isometric Hexagonal Tetragonal Orthorhombic Monoclinic Triclinic

How do we identify minerals? Physical o Hardness o its ability to resist scratching

How do we identify minerals? Physical o Hardness o its ability to resist scratching o Moh’s Scale of Hardness

How do we identify minerals? Physical o Specific Gravity o Relative weight of a

How do we identify minerals? Physical o Specific Gravity o Relative weight of a mineral when compared to the specific gravity of that mineral. The specific gravity of water is 1. 0.

How do we identify minerals? Physical o Cleavage o The way in which some

How do we identify minerals? Physical o Cleavage o The way in which some minerals will split or cleave precisely along planes related to the internal molecular structure.

Where does cleavage occur? o It occurs along certain planes of weakness that exist

Where does cleavage occur? o It occurs along certain planes of weakness that exist in some minerals because of their atomic structure. o Some minerals have cleavage in one, two, three, or more directions.

Fluorite

Fluorite

How do we identify minerals? Physical o Fracture o If a mineral breaks unevenly

How do we identify minerals? Physical o Fracture o If a mineral breaks unevenly along rough or curved surfaces instead of cleavage, this is called fracture.

How do we identify minerals? Physical o Color o The coloration of a mineral

How do we identify minerals? Physical o Color o The coloration of a mineral may be due to many factors, including chemical composition, trace elements, impurities, oxidation, and tarnishing.

These 3 are all colors of quartz.

These 3 are all colors of quartz.

How is color useful for identifying minerals? o The color of a mineral is

How is color useful for identifying minerals? o The color of a mineral is the first thing that people notice. o But it can also be the least useful in identifying a mineral. o Most minerals occur in more than one color, due to impurities or chemical differences. For example, fluorite can be clear, white, yellow, blue, purple, or green. Quartz also can be different colors.

For which minerals is color a useful tool for identification? o For some minerals,

For which minerals is color a useful tool for identification? o For some minerals, the color is due to the major elements and can be a characteristic way to identify a mineral. For example, malachite is always green, and azurite is always blue.

How do we identify minerals? Physical o Streak o When a mineral is rubbed

How do we identify minerals? Physical o Streak o When a mineral is rubbed against a a piece of unglazed porcelain tile, a streak of powder will result. The streak may differ from the color of the mineral and them become a valuable clue to its identification.

How do we identify minerals? Physical o Example: Hematite, for example always gives a

How do we identify minerals? Physical o Example: Hematite, for example always gives a reddish brown streak no matter what type of luster it displays.

How do we identify minerals? Physical o Luster o The surface of a mineral

How do we identify minerals? Physical o Luster o The surface of a mineral as it absorbs, reflects, or refracts light is termed luster o Metallic- Minerals with metallic luster look like metal, with a silvery appearance, or the flat metallic look of steel. o Non Metallic may look pearly, greasy, or glassy

Metallic Luster Pyrite Galena

Metallic Luster Pyrite Galena

What is Non-metallic Luster? o Some Non-metallic luster may look: n Pearly n Greasy

What is Non-metallic Luster? o Some Non-metallic luster may look: n Pearly n Greasy n Glassy Quartz

How do we identify minerals? Physical o Other Properties o Some minerals can be

How do we identify minerals? Physical o Other Properties o Some minerals can be identified by other unique characteristics. o Radioactivity (with a Geiger Counter) o Magnetism (with a magnet) o Fluorescence (Ultraviolet light)

There are 9 steps to mineral identification o o o o o Step 1:

There are 9 steps to mineral identification o o o o o Step 1: Determine the crystal form Step 2: Determine the hardness Step 3: Look up the specific gravity Step 4. Determine whether your mineral had cleavage (breakage). Step 5: Look at the fracture Step 6: Determine the color Step 7: Determine the streak color Step 8: Determine the luster Step 9: Look at other properties Name that mineral!

Mineral Identification

Mineral Identification

Let’s try to identify a few of our own…

Let’s try to identify a few of our own…