MINERAL PROPERTIES

Physical Properties
1. Color
  1. Color is one of the most obvious properties of a mineral but it is often of limited diagnostic value, especially in minerals that are not opaque. Never use color as a final diagnostic property.
2. Luster
  1. metallic luster
    1. look like a metal
  2. Vitreous luster
    1. is like that of glass, shiny and translucent to transparent. Remember that glass can be almost any color, including black, so don't be fooled by the color
  3. pearly luster
    1. have an appearance similar to a pearl
  4. earthy luster
    1. look like earth, or dirt
  5. waxy luster
    1. look like paraffin, typically translucent but dull
3. Streak
  1. Streak is obtained by scratching the mineral on an unpolished piece of white porcelain called a streak plate. Because the streak plate is harder than most minerals, rubbing the mineral across the plate produces a powder of that mineral. Streak is commonly more reliable than color for identification.
  2. Streak refers to the color of the mineral in its powdered form, which may or may not be the same color as the mineral. Streak is helpful for identifying minerals with metallic or earthy luster, because (with a few exceptions) minerals with nonmetallic luster generally have a colorless or white streak that is not diagnostic.
4. Hardness
  1. Hardness is the resistance of a mineral to scratching or abrasion by other materials. Hardness is determined by scratching the surface of the sample with another mineral or material of known hardness. The standard hardness scale, called Mohs Hardness Scale consists of ten minerals ranked in ascending order of hardness with diamond, the hardest known substance, assigned the number 10.
5. Cleavage and Fracture
6. Density
  1. Density= m/v
Chemical Properties
1. Reaction with Acid
  1. Some minerals, especially carbonate minerals, react visibly with acid. (Usually, a dilute hydrochloric acid [HCl] is used.)
2. Taste, Odor
  1. Some minerals have a distinctive taste (halite is salt and tastes like it). Some a distinctive odor (the powder of some sulfide minerals, such as sphalerite, a zinc sulfide, smells like rotten eggs).
Additional Properties
1. Special properties help identify some minerals. These properties may not be distinctive enough in most minerals to help with their identification. or they may be present only in certain minerals.
2. Magnetism
  1. Some minerals are attracted to a hand magnet. To test a mineral for magnetism, just put the magnet and mineral together and see if they are attracted.
3. Refringence
  1. The rays of light deviate from their trajectory when they pass through a transparent mineral. In some minerals, the ray of light splits in two (duplication of the image), a property known as birefringence.

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MINERAL PROPERTIES

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