1. Descriptions of Rock Forming Minerals: All the following minerals are made of silica tetrahedrons, either alone or combined with other elements

2. Quartz  Quartz (SiO 2 )is silicon dioxide. It has a glassy or greasy luster.  7 on Mohs hardness scale  Colour varies froms colourless or white, and pink rose quartz, purple amethyst, and brown or gray smoky quartz.  Quartz is the second most abundant mineral in Earth’s crust.  Quartz makes up much of sand and granites.

3. Feldspar  The most abundant family of minerals in Earth’s crust. (over 60%)  3 major properties:  Two directions of cleavage  6 on Mohs hardness scale  Pearly luster  Al ions have replaced some of the Si ions in the basic silica tetrahedron  The also have K, Na, and Ca ions.  Two major groups of feldspars: potassium feldspars and sodium calcite feldspars.  The most common potassium feldspar is orthoclase  The sodium-calcite feldspars are called plagioclase

4. Mica  Soft silicates found in many rocks  Flat shiny flakes are easily picked out of rocks such as granite and gneiss  Muscovite mica is silvery white  Biotite mica is dark brown or black  2.5 on Mohs hardness scale

5. Talc  The softest mineral  1 on Moh’s hardness scale  White, gray, or greenish in colour  One good cleavage and a soapy feel

6. Amphiboles  Complex silicate minerals that tend to form long, needlelike crystals  Hornblende is the most common, it is shiny dark green, brown, or black. It has two good cleavages at oblique angles, and a hardness of 5 to 6.  Hornblende is an example of a ferromagnesian silicate which all contain atoms of iron and magnesium.

7. Pyroxenes  Right angle cleavage surfaces  Augite is the most common member of the pyroxene family. It is a ferromagnesian silicate. Dark green, brown, or black. Two good cleavages, hardness 5 to 6.  Poorer luster than hornblende, short stout crystals

8. Olivine  Olive-green ferromagnesian silicate  Glassy shell-like in fracture  Very hard (6.5-7.5)  Found in some meteorites

9. Garnets  Dark red, brown, yellow, green, or black  Very hard (6.5-7.5)  Used as abrasives and gems

10. Kalinite or kaolin  Aluminum silicate  Formed from weathering of feldspar or other silicates  Principle mineral in clay and shale  Pure kaolin is white, but impurities make it yellow  Earthy (crumbly) fracture  Hardness between 1 and 2.5  Feels greasy and has earthy odour

11. Carbonate Minerals:Calcite and Dolomite  These minerals are not silica tetrahedrons  The carbonate group is CO 3 2-  A carbonate mineral is made of carbonate groups joined with various metal ions  Limestone and marble are carbonate minerals

12.  The most common carbonate mineral is calcite, calcium carbonate (CaCO 3 )  Pure calcite is colourless or white, impurities make it almost any colour  Hardness of 3  Three perfect oblique cleavages  Dolomite is calcium magnesium carbonate

13. Iron Oxides and Sulfides  Some minerals have large amounts of iron  Iron tends to be combined with either oxygen or sulfur to form an oxide or a sulfide  Hematite is the most common iron oxide mineral, it has a hardness of 5-6, is red with an earthy luster and crumbly fracture.

14.  Magnetite is a black magnetic iron oxide  Hardness 5.5-6.5  Lodestone is a highly magnetic variety  Pyrite is iron sulfide, it is the most common sulfide mineral  It has a golden colour and a metallic luster, and is commonly known as fool’s gold