Cinnabar

Formula:  HgS

Origin of name:  From Persian zinjifrah = dragon's blood, in Medieval Latin cinnabaris, name referring to the red colour

 

Crystal system:  Hexagonal

Crystal class:  32

Twinning:  Common on {0001}, contact; also about [1000] axis

Unit cell: a = 4.15 Ǻ, c = 9.50 Ǻ

 

Colour:  Scarlet, brownish red, brown, black, lead-gray

Diaphaneity:

Luster:  Adamantine, submetallic to dull

Habit:  Crystals rhombohedral to thick tabular, stout to slender prismatic; crystalline crusts, powdery coatings

Hardness:  2 to 2.5

Specific gravity:  8.09

Cleavage:  1; {10-10} perfect

Tenacity:  Conchoidal to uneven; brittle

Streak:  Scarlet to reddish brown

 

Synonyms/varieties:

 

Comments:  Trimorphous with metacinnabar and hypercinnabar. Formed from low-temperature hydrothermal solutions in veins, also in sedimentary,  igneous and metamorphic host rocks.

 

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