THE MINERAL KOTTIGITE

Chemistry: Zn3(AsO4)2-8(H2O) , Hydrated Zinc Arsenate
Class: Phosphates
Group: Vivianite
Uses: A very minor ore of zinc and mineral specimens
Specimens

Kottigite is a weathering product of zinc minerals such as sphalerite. Kottigite is isostructural with the minerals erythrite and annabergite. Isostructural means that the two minerals have the same structure but different chemistries. Annabergite, called "Nickel Bloom", is bright green. Erythrite, called "Cobalt Bloom". is bright red-purple. Kottigite is too rare to have nicknames like those of erythrite and annabergite. Those names were given to them by miners looking for cobalt and nickel minerals. Most kottigite, or as it is sometimes spelled, koettigite, is found at Mapimi, Mexico and Schneeburg, Germany.

PHYSICAL CHARACTERISTICS:

Color is brown to reddish or white and gray.
Luster is vitreous.
Transparency: Crystals are transparent to translucent.
Crystal System is monoclinic; 2/m
Crystal Habits include flattened striated blades or radiating accicular crystals, but crystals are uncommon. More commonly as crusts or earthy masses.
Cleavage is perfect in one direction.
Fracture is uneven.
Hardness is 2.5 - 3
Specific Gravity is approximately 3.3 (average for translucent minerals)
Streak is pale brown.
Associated Minerals are limonite, smithsonite, adamite and other zinc minerals.
Other Characteristics: Blades are somewhat flexible.
Notable Occurrences include Mapimi, Durango, Mexico and Schneeberg, Germany.
Best Field Indicators are color, associations and crystal habit.