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Gemstones 250x250

The Mineral pararealgar

Pararealgar Alteration of Realgar

Pararealgar is the alteration product of the mineral Realgar. It forms when Realgar is exposed to light, which causes a physical change in the structure of the mineral and transforms it into a new mineral. Pararealgar is has the same chemical composition and chemical formula as Realgar, but its crystal form differs. Pararealgar is also different in color than Realgar; whereas Realgar is bright red, Pararealgar is bright orange or yellow, and additionally has a more powdery consistency.

Pararealgar is usually associated with Realgar, and specimens can be partially altered. It is not uncommon for specimens to be only partially altered in sections, creating yellow and red color zones. Once a significant alteration has taken place, the mineral will start to crumble. The alteration mineral that Realgar transformed into was generally assumed to be Orpiment, but recent scientific analysis has in fact determined the orange alteration product as Pararealgar. Pararealgar, like Realgar, is photosensitive, and will become unstable and eventually crumble into a yellow powder if left in the light. Specimens should be stored enclosed and covered to prevent their exposure to light.

Pararealgar contains a significant amount of poisonous arsenic, and is itself somewhat toxic. Washing hands is recommended after handling specimens, especially if they are powdery.

Chemical Formula

AsS

Color

Yellow to orange

Crystal System

Monoclinic

Properties

Streak
Yellow
Hardness
1 - 1.5
Transparency
Translucent
Specific Gravity
3.5 - 3.6
Luster
Resinous to earthy
Cleavage
None
Fracture
Uneven
Tenacity
Brittle
Other ID Marks
Eventually decomposes into powder upon repeated or prolonged exposure to light.

Crystal Habits

As a crusty powder, massive, and on altering Realgar crystals.

Additional Information

Composition
Arsenic sulfide
In Group
Sulfides; Simple Sulfides
Striking Features
Association with Realgar and color.
Environment
Found in the same deposits as Realgar as an alteration of Realgar.
Rock Type
Igneous, Sedimentary, Metamorphic

Uses

As an ore of arsenic together with Realgar.

Noteworthy Localities

Pararealgar localities are the same as Realgar localities. Click here for Realgar localities.

Common Mineral Associations

Realgar, Orpiment, Calcite, Quartz, Barite, Cinnabar, Stibnite, Ulexite, Colemanite

pararealgar Photos



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