Mineral Identification

Identifying Minerals: Minerals have chemical and physical properties that are unique to each mineral Physical Properties Color Color Luster Luster Density/specific gravity Density/specific gravity Texture Texture Chemical Properties Cleavage Cleavage Hardness Hardness Special properties (reaction w/hydrochloric acid) Special properties (reaction w/hydrochloric acid)

Crystalline Structure ALL minerals are crystalline. ALL minerals are crystalline. A crystal is a regular geometric solid with crystal faces. A crystal is a regular geometric solid with crystal faces. Out of thousands of different minerals, only six basic crystal forms can form. Out of thousands of different minerals, only six basic crystal forms can form.

Crystal Shape/Form The orderly arrangement of the atoms or ions in the mineral determine its crystal shape. The orderly arrangement of the atoms or ions in the mineral determine its crystal shape. The alignment and strength of the bonds between the atoms determine hardness, cleavage, crystal shape, streak, etc. The alignment and strength of the bonds between the atoms determine hardness, cleavage, crystal shape, streak, etc.

Six Crystal Forms Cubic Cubic Orthorhombic Orthorhombic Tetragonal Tetragonal Triclinic Triclinic Hexagonal Hexagonal Monoclinic Monoclinic

Color While helpful not always a reliable feature. While helpful not always a reliable feature. For example: fluorite & quartz For example: fluorite & quartz Fluorite

Luster The way a mineral reflects light The way a mineral reflects light Metallic or non-metallic Metallic or non-metallic

Hardness Hardness is how easily a mineral can be scratched. Hardness is how easily a mineral can be scratched. Talc can be scratched with your fingernail, while diamonds can cut glass. Talc can be scratched with your fingernail, while diamonds can cut glass.

Moh’s Hardness Scale Moh’s Hardness Scale Categorizes minerals by hardness Categorizes minerals by hardness Ranges from 1(softest) to 10 (hardest) Ranges from 1(softest) to 10 (hardest) Hardest mineral = Diamond Hardest mineral = Diamond Softest mineral = Talc Softest mineral = Talc

Moh’s Hardness Scale

Streak Is the color of a mineral when powdered. Is the color of a mineral when powdered. When a mineral is rubbed across a porcelain tile a streak of a particular color will be left. When a mineral is rubbed across a porcelain tile a streak of a particular color will be left.

Cleavage and Fracture Cleavage and Fracture If a mineral splits along planes of its surfaces, it has cleavage. If a mineral splits along planes of its surfaces, it has cleavage. If a mineral leaves a jagged edge it is said to have fracture. If a mineral leaves a jagged edge it is said to have fracture.

Other Properties Some minerals have characteristics unique to them. Some minerals have characteristics unique to them. Magnetite is attracted to magnets. Magnetite is attracted to magnets. Calcite fizzes with acid and splits images into two separate images when looking through a sample. Calcite fizzes with acid and splits images into two separate images when looking through a sample.