Carnelian

Real mineral · common · SiO₂

A red-orange variety of chalcedony coloured by iron oxide. Forms in volcanic and sedimentary environments. Its uniform translucency and lack of internal structure made it a preferred material for carved seals and intaglios.

Identity

Formula

SiO₂

Chemical class

silicate

Mineral group

Amethyst, Bloodstone, Chalcedony, Citrine, Quartz, Rose Quartz, Smoky Quartz, Tiger's Eye

Also known as

Cornelian, Sard (darker brownish variety)

Crystallography

Crystal system

trigonal

Habits

massive, nodular

Fracture

conchoidal

Physical properties

Mohs hardness

7

Density

2.62 g/cm³

Luster

vitreous, waxy

Colors

red, orange-red, reddish brown

Streak

white

Transparency

translucent

Geology

Origins

sedimentary, hydrothermal

Host rocks

basalt, alluvial deposits

Associated minerals

Chalcedony, Quartz, Chalcedony

Geography

India, Brazil, Uruguay, Egypt, Madagascar

Classification

Rarity

common

Gem quality

Yes

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