Mineral Identification Lab

Assignment: Activity 2, A-I, Skip H 2 and 3, pg 68; Identify all the minerals in the tray provided. Fill out Mineral Data Chart pg. 71.

A mineral is defined as being:

    1. _________________________
    2. _________________________
    3. _________________________
    4. _________________________
    5. _________________________

A rock on the other hand, is an aggregate of _____________________ minerals.

 

The identification and recognition of minerals are based on certain ____________ _____________ which they exhibit. Some of these physical properties are: Luster, Color, Hardness, Streak and Cleavage.

Luster is the way a freshly broken mineral surface reflects ________________. Minerals which look like metal when they reflect light are said to have a __________________ luster. Non-metallic looking minerals may be described using terms such as vitreous (glass-like), resinous, pearly, silky, dull, waxy, greasy, earthy, brilliant, etc.

Color is also determined by examining a fresh mineral surface. Color is only a diagnostic feature in some minerals since it may vary greatly due to slight differences in ________________ _______________ or traces of ______________.

Hardness is a minerals's resistance to being _________________. The degree of a mineral's hardness is measured on a scale of 1 to 10, known as Moh's hardness scale, where 1 is the ____________ and 10 is the _____________. Ten common minerals represent each of the numbers of the scale. It can be determined if a mineral is harder or softer than another substance (such as glass or fingernail) simply by trying to scratch it with the mineral.

Moh's Hardness Scale

    1. ________
    2. Gypsum- fingernail
    3. Calcite- penny (copper)
    4. Fluorite- nail
    5. Apatite- glass
    6. Orthoclase feldspar (K-feldspar)
    7. ____________
    8. Topaz
    9. Corundum
    10. _____________

Streak is the color of the mineral in its ___________________ form. It can be powdered by rubbing it against a piece of unglazed porcelain known as a streak plate. A small residue of the mineral will wear off on the plate. This test is especially useful for identifying minerals with a ______________ luster.

Cleavage is a mineral's tendency to break along definite planes of _________________ that exist due to the mineral's _____________. Cleavage may exist, but not be obvious. Often, a mineral with cleavage will display it in more than one direction. Cleavage must not be confused with crystal face surfaces which is a natural growth pattern.

Other physical properties include:

specific gravity- how heavy a mineral feels compared to its size

magnetism- a mineral's attraction to a magnet

taste- such as the mineral halite which will taste salty

feel- soapy, greasy, etc.

reaction to hydrochloric acid- (such as calcite) it bubbles with the release of carbon dioxide

odor- such as the earthy smell of kaolinite in high humidity and sulphur smell of sphalerite and pyrite

fluorescence- under UV light some minerals glow with a characteristic color such as calcite.

striations- straight, parallel lines on the mineral's surface which resemble scratches

habit- the characteristic appearance or form of mineral having to do with the manner in which they form. Some common examples of habit are:

  • micaceous- composed of small flecks
  • massive- having no specific shape, composed of compact microscopic crystals
  • crystalline- composed of many interlocking crystals.