Chemical: Cu2(CO3)(OH)2 (Hydrous copper carbonate)
Malachite is a green colored copper mineral that occurs in many forms. It belongs to the monocline crystal system and has a hardness of 3.5 to 4. Some types of malachite are the “Druse or Druzy”, which has very fine-grained crystals like grains of sand and the “velvet”, a fibrous form that looks like crushed velvet. Malachite also occurs in stalagmite masses. Individual crystals can be found, but are rare.
Malachite is mainly in the oxidation zone of copper deposits. It is also found dispersed in sandstones deposited by swift moving ground water.
Druse or Druzy is a fine coating of crystals that form on rocks and minerals. These crystals are very tiny and very numerous giving a specimen a sparkling appearance. Druse can also found on the interior of quartz geodes. Ground water carrying dissolved silica (silicon dioxide) is forced into porous areas of rocks and then rapidly cools. This process over time causes the formation of tiny crystals on the surfaces or in cavities of the stone. This process can occur on other minerals and rocks such as calcite, carnelian, chrysocolla, cobalt, hematite, malachite, and ocean jasper, to name a few.