Minerals, part ????

Go to the following web site:

http://www.bhc.edu/academics/science/harwoodr/Geol101/

Read the information, then click on the link named "LAB MATERIAL", then click on "Mineral Physical Properties and Mineral Identification".

Read the information on this page, continue to the page bottom and do the mineral identification exercises (20 in all).
Try to identify the unknown minerals using the various properties listed. You may have to go back and check the list to verify.

If you have trouble, click on the lecture material link and then the Mineral Systems and Physical Properties links for background information.

After you've completed this much, use the properties below to try and identify the minerals. Write them on a separate sheet of paper and hand them in to me today.

1. Imperfect in three directions (rhombic) Hardness = 1� to 2� resinous to sub-vitreous, may appear somewhat earthy when massive or as crusts; Bright-yellow; Orthorhombic crystals; usually crystallized masses. Usually gives a pale yellow streak.

2. Perfect in one direction (rarely seen) Hardness = 2 to 2� earthy White to Tan, may be Greyish or pink; usually as compact earthy masses; has an earth odor when moistened.

3. Cleavage is Perfect in three directions, none at 90 degrees (rhombic); Hardness = 3; usually Clear or White to Tan or Grey, but may be tinted many colors vitreous to sub-vitreous. Trigonal crystals may be in cleavable masses producing rhombs, granular masses (limestone and marble),scalenohedral ("dogtooth") crystals, rhombohedral crystals, flattened rhombohedral ("nailhead") crystals, or a wide variety of related shapes; White streak; clear rhombs show a doubled image of print viewed through them, effervesces (fizzes) in cold, dilute acid � even in vinegar or Coke to a small degree.

4. Six cleavage directions - perfect in all six directions, dodecahedral; Hardness = 3� to 4 Brown to Black, Yellow-brown to Greenish-yellow-brown, may also be Red in small crystals resinous, but may be oily or sub-metallic on cleavage surfaces and adamantine in small crystals. Isometric crystals usually in coarsely crystalline cleavable masses exhibiting seemingly chaotic cleavage surfaces and as small tetrahedral (wedge-shaped) or dodecahedral (soccer ball-shaped) crystals; larger crystals tend to be somewhat crude and rough surfaced aggregates; brown to yellow streak.

5. Perfect in one direction, good in the second (prismatic) 6 to 6� White to Light-grey and Colorless, may be tinged blue or green, darkening to Dark-grey to Black. Vitreous luster; members on this end of this group are most easily distinguished from others in this group by fine, closely-spaced striations on a cleavage surface.

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