Carnelian (2) Raw Minerals Stones Rocks Collecting

Description

Origin : Brazil

Carnelian 31-50 gr - cm 3-5.5 Raw Minerals Stones Rocks for Collection.

Carnelian is a well-known variety of chalcedony, itself a member of the cryptocrystalline quartz family. Agate, onyx, heliotrope and chrysoprase belong to the same family. It is a silicon dioxide (formula SIO2), crystallizes in the monoclinic system and the crystals have a conchoidal fracture.
Its most valuable color is red-orange, due to the presence of iron oxides, while the lighter shades are attributable to iron hydroxide. If the mineral is subjected to a slight heating, its color becomes more intense and then returns to its original color when the heat source is removed.
The hardness is 7 on the Mohs scale, as for all quartzes, and this fact makes it very suitable for engraving work as well as for the production of spheres for necklaces.
The best known deposits, formerly exploited by the Romans, were those located in India, Arabia and Persia. Carnelian is currently mined in South America in the Brazilian state of Rio Grande do Sul and in Uruguay.