Mineral Groups in the Earth’s Crust

Reference: Pages 44 - 55

Minerals that form the rocks within Earth’s crust belong to Seven (7) main mineral groups:

1) Silicates

2) Carbonates

3) Sulfates

4) Oxides

5) Halides

6) Sulfides

7) Native

Hints to Classify Mineral Groups

Olivine (Mg,Fe)2SiO4

Barite BaSO4

Calcite CaCO3

Mineral groups that end with “ate” and have an oxygen group in its chemical formula are one of the following;

Silicates = Si + Ox

Sulfates = S + Ox

Carbonates = C + Ox

A

Hints to Classify Mineral Groups

Hematite Fe2O3

Pyrite FeS2

Fluorite CaF2

Mineral groups that end with “ide” and have a metal (eg. Na, K) in its chemical formula are one of the following;

Oxidides = Metal + O

Sulfides = Metal + S

Halides = Metal + Cl, Br, F

B

Mineral GroupsSilicates1)

Silicon and oxygen are the most common elements in earth’s crust.

A mineral group that has silicon and oxygen as part of their atomic structure.

The most dominant mineral class is the silicates.

Comprise more than 96% of the crust.

All silicate minerals have the same building block:

Silicon-Oxygen Tetrahedron- consisting of four oxygen ions (negative) surrounding one small silicon ion (positive), forming a tetrahedron, a pyramid shape with 4 identical faces.

Mineral GroupsSilicates1)

Mineral GroupsSilicates1)

Rock forming Silicates are divided into two (2) groups:

Sialic Silicates (Aluminosilicates) rich in silicon and aluminum.

main rock type found in continents and comprise about 85% of the crust.

mineral are light in color.

Mineral GroupsSilicates1)

Rock forming Silicates are divided into two (2) groups:

Simatic Silicates (Ferromagnesium) rich in silicon and magnesium (Iron).

main rock type found in the ocean floor and comprise less than 15% of the crust.

mineral are dark in color.

Mineral GroupsCarbonates2) compounds consisting of an atomic structure of one carbon and three oxygen (CO3).

most common carbonate is calcite which make up the rock Limestone. (Ca CO3)

Sulfates3) compounds consisting of an atomic structure of one sulfur and four oxygen (SO4).

the rock Gypsum is an example of a sulfate and it also takes on the mineral name. (CaSO4 2H2O)

Mineral GroupsOxides4) compounds consisting of an atomic structure of oxygen combined with one or more metals.

most common oxides are those of iron (Fe2O3) and aluminum (Al2O3), referred to as Ore - Minerals.

Halides5) compounds consisting of an atomic structure of chlorine or fluorine with sodium, potassium, or calcium.

Halite (NaCl) is the most common halide. Often referred to as table salt.

Mineral GroupsSulfides6) compounds consisting of an atomic structure of one or more metals combined with sulfur.

common ore mineral. Examples: Pyrite (FeS2), Galena (PbS), Sphalerite (ZnS).

Native Minerals7) elements that occur uncombined in nature.

commonly called native elements.

Examples: Gold (Au), Silver (Ag), Copper (Cu), & Sulfur (S)

Worksheet

• Identifying mineral groups by chemical formulas

Sample Problem

Which is an example of a halide?

(A) barite (BaSO4) (B) calcite (CaCO3) (C) fluorite (CaF2) (D) hematite (Fe2O3)

Questions related to this topic are commonly seen in the multiple choice.