Minerals

Amphibole (Hornblende)

A black mineral with non-metallic luster, hardness >5.5, and two cleavage planes at about 120°.

Biotite Mica

A black sheet silicate mineral with one perfect cleavage plane that splits into thin sheets.

Calcite

A mineral with hardness 3, rhombohedral cleavage, and the ability to react with hydrochloric acid.

Corundum

A very hard mineral (hardness 9) that commonly forms hexagonal prism crystals.

Dolomite

A carbonate mineral with rhombohedral cleavage that reacts weakly with acid when powdered.

Fluorite

A mineral with hardness 4 and four cleavage planes forming octahedral shapes.

Galena

A dense metallic mineral with silver-gray color and cubic cleavage at 90°.

Garnet

A hard mineral with no cleavage and a typical dodecahedral crystal shape.

Graphite

A very soft mineral (hardness 1) with a black streak that can write on paper.

Gypsum

A soft mineral (hardness 2) with one prominent cleavage plane that can be scratched by a fingernail.

Halite

A cubic mineral with salty taste and three cleavage planes at 90°.

Hematite

A metallic or earthy mineral with a distinctive red-brown streak.

Kyanite

A blue mineral with bladed crystals and one perfect cleavage plane.

Magnetite

A magnetic mineral with metallic luster and a dark streak.

Muscovite

A transparent mica mineral that splits easily into thin sheets.

Olivine

A green mineral with hardness 7 and no cleavage, commonly found in mafic rocks.

Plagioclase Feldspar

A feldspar mineral with two cleavage planes at 90° and often visible striations.

Potassium Feldspar (Orthoclase)

A feldspar mineral with two cleavage planes at 90°, often pink and showing lamellae.

Pyrite

A metallic mineral known as “fool’s gold,” with cubic crystals and greenish-black streak.

Pyroxene (Augite)

A dark mineral with two cleavage planes at 90° and blocky crystals.

Quartz

A hard mineral (hardness 7) with conchoidal fracture that scratches glass.

Sulfur

A soft yellow mineral that smells like rotten eggs when scratched.

Talc

The softest mineral (hardness 1) with a soapy or powdery feel.