Comparison · Sulfide Minerals
Realgar vs Stibnite
Realgar and Stibnite are easy to confuse because both are sulfide minerals. Both sit near Mohs 1.75, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Realgar and Stibnite
- Both sit near Mohs 1.75, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Realgar leaves a orange-red to yellow-orange streak on unglazed porcelain, Stibnite leaves lead gray.
- Luster is different: Realgar is resinous while Stibnite is metallic.
- Stibnite feels noticeably heavier for its size (specific gravity 4.6 versus 3.56 for Realgar).
- Hold a thin edge to the light: Realgar is translucent, Stibnite is opaque.
- Well-formed crystals give it away: Realgar is monoclinic, Stibnite is orthorhombic.
Realgar vs Stibnite properties
| Property | Realgar | Stibnite |
|---|---|---|
| Type | Sulfide Minerals | Sulfide Minerals |
| Mohs hardness | 1.75 | 2 |
| Luster | resinous | metallic |
| Streak | Orange-red to yellow-orange | Lead gray |
| Transparency | translucent | opaque |
| Specific gravity | 3.56 | 4.6 |
| Crystal system | monoclinic | orthorhombic |
| Common colors | Red, Orange-red, Orange | Lead gray, Steel gray, Silvery gray |
| Rarity | uncommon | uncommon |
| Typical specimen value | $10–$450+ | $10–$1500+ |
Which is more valuable?
Stibnite is usually the more valuable of the two: a typical collector specimen runs about $120 against $70 for Realgar, and premium Stibnite can reach $1500 or more.
About Realgar
Realgar is an arsenic sulfide mineral famous for its brilliant orange-red to red color and resinous luster. It forms soft, often translucent crystals and granular crusts, and slowly breaks down to a powder when exposed to light.
About Stibnite
Stibnite is antimony sulfide, the chief ore of antimony. It is famous for brilliant steel-gray metallic crystals that form long, slender, often curved or radiating prismatic blades with perfect lengthwise cleavage.
Realgar vs Stibnite FAQ
Is Realgar the same as Stibnite?
No. Both are sulfide minerals, but they are distinct species with different hardness, streak or luster. Both sit near Mohs 1.75, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Realgar from Stibnite?
Both sit near Mohs 1.75, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Realgar leaves a orange-red to yellow-orange streak on unglazed porcelain, Stibnite leaves lead gray. Luster is different: Realgar is resinous while Stibnite is metallic.
Which is harder, Realgar or Stibnite?
They are about equally hard, both near Mohs 1.75.
Which is more valuable, Realgar or Stibnite?
Stibnite is usually the more valuable of the two: a typical collector specimen runs about $120 against $70 for Realgar, and premium Stibnite can reach $1500 or more.
