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Physical Properties — Mineral Appearance

Mineral Identification. 2. Physical Properties — Mineral Appearance. Color and appearance are two obvious clues that can be used to identify minerals. Some other properties to study include how hard a mineral is, how it breaks, and its color when crushed into a powder. Mineral Identification.

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Physical Properties — Mineral Appearance

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  1. Mineral Identification 2 Physical Properties— Mineral Appearance • Color and appearance are two obvious clues that can be used to identify minerals. • Some other properties to study include how hard a mineral is, how it breaks, and its color when crushed into a powder.

  2. Mineral Identification 2 Hardness • A measure of how easily a mineral can be scratched is its hardness. • Sometimes the concept of hardness is confused with whether or not a mineral will break. • It is important to understand that even though a diamond is extremely hard, it can shatter if given a hard blow in the right direction along the crystal.

  3. Mineral Identification 2 Mohs Scale • In 1824, the Austrian scientist Friedrich Mohs developed a list of common minerals to compare their hardnesses. • This list is called Mohs scale of hardness.

  4. Mineral Identification 2 Luster • The way a mineral reflects light is known as luster. • Luster can be metallic or nonmetallic. • Minerals with a metallic luster shine like metal.

  5. Mineral Identification 2 Luster • When a mineral does not shine like a metal, its luster is nonmetallic. • Terms for nonmetallic luster include dull, pearly, silky, and glassy.

  6. Mineral Identification 2 Specific Gravity • Minerals also can be distinguished by comparing the weights of equal-sized samples. • Thespecific gravity of a mineral is the ratio of its weight compared with the weight of an equal volume of water. • Specific gravity is expressed as a number.

  7. Mineral Identification • Streak is the color of a mineral when it is in a powdered form. 2 Streak • When a mineral is rubbed across a piece of unglazed porcelain tile, a streak of powdered mineral is left behind.

  8. Mineral Identification 2 Streak • The streak test works only for minerals that are softer than the streak plate. • Some soft minerals will leave a streak even on paper. • The last time you used a pencil to write on paper, you left a streak of the mineral graphite.

  9. Mineral Identification 2 Cleavage and Fracture • The way a mineral breaks is another clue to its identity. • Minerals that break along smooth, flat surfaces have cleavage (KLEE vihj). • Cleavage is determined partly by the arrangement of the mineral’s atoms.

  10. Mineral Identification 2 Cleavage and Fracture • Not all minerals have cleavage. • Minerals that break with uneven, rough, or jagged surfaces have fracture. • Quartz is a mineral with fracture.

  11. Mineral Identification 2 Other Properties • Some minerals have unique properties. • Magnetite is attracted to magnets.

  12. Mineral Identification 2 Other Properties • Quartz Light forms two separate rays when it passes through calcite, causing you to see a double image when viewed through transparent specimens.

  13. Minerals 2 Question 1 The Mohs scale uses __________ to compare minerals. A. cleavage B. color C. hardness D. luster

  14. Minerals 2 Answer The answer is C. The Mohs scale, developed by Friedrich Mohs, rates the hardness of minerals from one to ten.

  15. Minerals 2 Question 2 Minerals that break easily along smooth, flat surfaces have __________. A. cleavage B. fracture C. luster D. streak

  16. Minerals 2 Answer The answer is A. Cleavage is determined partly by the arrangement of the mineral’s atoms. Minerals that break with uneven surfaces have fracture.

  17. Minerals 2 Question 3 Which of the following minerals will pick up iron filings? A. calcite B. feldspar C. lodestone D. quartz

  18. Minerals 2 Answer The answer is C. Lodestone is a variety of magnetite and is a natural magnet.

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