Definition

Noun: 1. A rare, soft, orange-red mineral: A naturally occurring mineral composed primarily of arsenic sulfide (As₄S₄ or AsS). It is known for its distinctive orange to reddish color and softness. 2. An ore of arsenic: Historically, it has been an important source of arsenic.

Usage

Realgar is used as a singular, countable noun. It refers specifically to the mineral itself, either as a geological specimen or as a historical source material.

Examples

• Geologists identified the bright orange crystals in the vein as realgar.
• Realgar and orpiment (arsenic trisulfide) are often found together in hydrothermal deposits.
• Ancient artisans used powdered realgar as a pigment, though it is toxic.
• The museum's collection features a fine specimen of realgar on calcite.

Advanced Usage

• Historical/Alchemical Context: In historical and alchemical texts, realgar is often mentioned alongside other arsenic minerals for its use in pigments, medicines (despite its toxicity), and metallurgy.
  • Alchemists in medieval China experimented with realgar in their search for elixirs.

Variants and Related Words

• Orpiment (noun): A yellow mineral, arsenic trisulfide (As₂S₃), frequently associated with realgar.
• Arsenic (noun): The chemical element (As) for which realgar is an ore.
• Mineral (noun): A naturally occurring, inorganic solid with a definite chemical composition and crystalline structure.

Synonyms

• Ruby sulfur (an archaic name)
• Red arsenic sulfide (descriptive chemical name)

Notes on Meaning

The term realgar refers exclusively to the mineral form of arsenic sulfide. It is not used as a general term for the color orange or for synthetic arsenic compounds. Its primary contexts are mineralogy, geology, and the history of science/art.

Noun

1. a rare soft orange mineral consisting of arsenic sulphide; an important ore of arsenic