Minerals.net Menu

The Mineral metacinnabar

Metacinnabar on Quartz

Metacinnabar is an uncommon polymorph of the mineral Cinnabar, forming in a different crystal system. In addition to its crystal forms, Metacinnabar also visually differs from Cinnabar, having a metallic luster, gray color, and lack of transparency.

Chemical Formula

HgS

Color

Metallic gray

Crystal System

Isometric

Properties

Streak
Gray to black

Hardness
3

Transparency
Opaque

Specific Gravity
7.7 - 8.1

Luster
Metallic

Cleavage
None

Fracture
Uneven

Tenacity
Brittle to slightly sectile

Crystal Habits

In small and usually distorted equant crystals in the form of complex tetrahedral and pyritohedral forms. Crystals are sometimes rounded and usually striated. Also platy, in small crystal clusters, in rounded balls, and encrusting.

3D Crystal Atlas

Additional Information

Composition
Mercury sulfide

In Group
Sulfides; Simple Sulfides

Striking Features
Crystal habits, color, and mode of occurence.

Environment
In volcanic, mercury-rich deposits usually associated with hot springs, and in epithermal veins.

Rock Type
Igneous

Other Names

Metacinnabarite

Varieties

Onofrite

- Selenium-rich variety of Metacinnabar, with selenium partially replacing the sulfur. Described from San Onofre, Plateros, Zacatecas, Mexico.

Uses

As a minor ore of mercury in mercury deposits.

Noteworthy Localities

Metacinnabar is uncommon and there are sporadic occurrences in many of the important mercury deposits. The most significant locality of this mineral is Mount Diablo in the Diablo Range, Contra Costa Co., California.