Amethyst

Amethyst is the most valuable variant within the quartz family. The crystals are always anchored to a base. The base is usually agate. The purplish color of this sample of amethyst is caused by atomic impurities found inside the crystal. Geologists do not know what these impurities are, but manganese, iron and sulfur are likely culprits.

Amethyst can be found in geodes and alluvial deposits.

Color: Purple, violet, pale red-violet

Color of streak: White

Moh’s hardness: 7

Density: 2.65 grams/cubic centimeter

Cleavage: None

Fracture: Conchoidal, very brittle

Crystal system: Hexagonal prisoms

Chemical composition: SiO2, silicon dioxide

Transparency: Transparent

Refractive index: 1.544-1.553

Double refraction: +0.009

Dispersion: 0.013 (0.008)

Pleochroism: Weak, reddish-violet, gray-violet

Absorption spectrum: (550-520)

Fluorescence: Weak, bluish