You can find minerals almost anywhere. Many minerals are
abundant and many have important uses
Minerals are grouped into families according to the elements in them
Quartz
• Chemical formula - silicon dioxide• Colorless or white• Hardness of 7• Used in watch movements, prisms, lenses
and jewelry
Feldspars
• Contains silicon, oxygen and aluminum• Makes up 60% of the Earth’s crust• Hardness of 6• Cleavage (quartz doesn’t have cleavage)• Classified into 2 groups: potassium (pink) and sodium
(white or gray) feldspars• Used to make paint
Mica
• Very soft silicates (2.5)• Cleaves into flat sheets• Muscovite – white, contains aluminum• Biotite – black, contains iron• Rock-forming mineral
Calcite
• Most common carbonate mineral (calcium carbonate)
• Colorless or white• Hardness of 3• Three directions of cleavage• Reacts with hydrochloric acid
Dolomite
• Contains calcium magnesium carbonate• Hardness of 3.5 – 4• Cleavage (3 directions)• Reacts with hydrochloric acid, but only in powder form
Hematite
• Most common iron oxide• Uneven fracture • Earthy luster, but some samples have a metallic silver
luster• Hardness of 5-6• Red streak
Magnetite
• Iron oxide• Is magnetic• Hardness of 5.5-6.5• Because of its magnetic properties, magnetite
was used to make the first compass (lodestone)