Mineral Classification

There are over 3,000 minerals but only 30 are common. To keep them organized, they are classified into groups based on chemical composition. – In other words, they are put into groups based on what elements they are made of.

4 Common Elements Oxygen (O) – 47% Silicon (Si) – 28% Aluminum (Al) – 8% Iron (Fe) – 5%

4 other common minerals Calcium (Ca) – 4% Sodium (Na) – 3% Potassium (K) – 2.5% Magnesium (Mg) – 2% All others – 1.5%

1) Silicates are the most common Most common minerals are silicates including: – Quartz – Feldspar – Mica They make up 90% of the crust.

Silicates form from 4 oxygen atoms surrounding a single silicon atom in a tetrahedron shape. The molecule is negatively charged, so it can bond to positively charged elements like iron, aluminum, calcium, and sodium.

2) Oxides – form from a metal bonding to oxygen. They include the major ores of iron and aluminum. – Magnetite is Fe 3 O 4 - Hematite is Fe 2 O 3

3) Carbonates contain a carbon, an oxygen, and 1 or more metals. Most carbonates are either calcites or dolomites. (They both react with hydrochloric acid.) CaCO 3

4) Sulfides – contain sulfur and a metal. Many ores are sulfides including Pyrite (FeS 2 )

5) Sulfates include sulfur, an oxygen, and metals. Many minerals are sulfates, but few are common. Gypsum is a common sulfate.

6) Halides – contain chlorine or fluorine with calcium, sodium, or potassium. They include salt (NaCl) and flourite (CaF 2 ) The mineral name for salt is halite.

7) Native Elements – contain only 1 element Examples include gold, silver, copper, and platinum.

Classify the following minerals by their composition: Galena (PbS) ______________________ Sulfur (S) _________________________ Calcite (CaCO 3 ) __________________ Potasium Feldspar (KAlSi 3 O 8 ) ___________KAlSi O