Malachite

Malachite is a from carbonates group.
Opaque, usually in bands in green colors and forms stalagmites.
Sometimes found with copper ore, it is found a lot of times with azurite, goethite and calcite.
Malachite is more common then azurite and is typically associated with copper ores together with limestone.
It is used for it's copper and in jewelry.

Chemical formula: Cu2CO2(OH)2
Composition: 57,48% copper; 0,91% hydrogen; 5,43% carbon; 36,18% oxygen; 71,95% CuO; 8,15% H2O; 19,90% CO2
Crystal sistem: Monoclinic
Colors: green, white-green, dark green, can be translucid on thin samples
Fracture: subconchoidal to uneven
Cleavage: perfect
Hardness: 3,5-4 Mohs
Streak: light-green
Specific gravity: 3,6-4
Optical proprieties: biaxial (-)
Density: 3,6-4; average 3,8

Asociated with azurite, Crysocolla, Chalcopyrite, limonite, copper, calcite and quartz.

Distinguishing similar minerals:
Brochantite - very look like having the same hardness and streak but this one is a sulfate; malachite becomes effervescent in warm hydrochloric acid while Brochantite does not; crystals are more alongated but still hard to distinguish
Antlerite is identical with brochantite and malachite and is very hard to distinguish without complex tests.
Antlerite doest not become effervescent in hydrochloric acid.
 Dioptase has a similar color but not the same light streak and different hardness.

Malachite and azurite has similar chemical formula (Cu2CO2(OH)2 vs Cu3(CO2)2(OH)2).
They usualy grow close to each other and sometimes mix.
Malachite can replace azurite's crystals altering it chemicaly.

Tests:
Malachite does effervescent in warm hydrochloric acid
Has a hardness of 3,5-4 Mohs
Has a light green streak

Malachite was used in antiquity up to year 1800.
In 17 decade, Spanish superstitions said that malachite protects people in their sleep from negative spirits.

Malachite amulet

Sources:
https://www.minerals.net/mineral/malachite.aspx
https://www.mindat.org/min-2550.html
http://webmineral.com/data/Malachite.shtml#.XaiNPOgzbvM

Other names: malachite malachit malachitul