Natural Carnelian Stone

Weight: 182.8 gram

Size:  86x65x30 mm

This stone is from Brazil.

***

Carnelian

Category  Chalcedony variety

Chemical formula  Silica (silicon dioxide, SiO2)

Molar mass  60 g / mol

Color  Brownish-red

Crystal system  Trigonal

Cleavage  Absent

Fracture  Uneven, splintery, conchoidal

Mohs scale  hardness 6 - 7

Luster  Vitreous, dull, greasy, silky

Streak  White

Diaphaneity  Translucent

Specific gravity  2.59 - 2.61

Carnelian, also called cornelian,  a translucent, brownish-red, semiprecious variety of the silica mineral chalcedony that owes its red to reddish brown colour to colloidally dispersed hematite (iron oxide). It is a close relative of sard, differing only in the shade of red. Carnelian was highly valued and used in rings and signets by the Greeks and Romans, some of whose intaglios have retained their high polish better than many harder stones. Carnelian’s colour is enhanced by baking and dyeing with iron salts. Chief localities are Ratnapura, India; Campo de Maia, Braz.; and Warwick, Queens., Austl. Its physical properties are those of quartz.

Stones may be uniformly colored or faintly banded. The best carnelian is from India, where it is placed in the sun to change from brown to tints to red. Most carnelian on the market is stained chalcedony from Brazil or Uruguay.