Comparison · Minerals
Celestine vs Gibbsite
Celestine and Gibbsite are easy to confuse because both are minerals. Both sit near Mohs 3–3.5, 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 Celestine and Gibbsite
- Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Celestine feels noticeably heavier for its size (specific gravity 3.95–3.97 versus 2.3–2.4 for Gibbsite).
- They overlap in gray and green, but Celestine also comes in clear, blue, and orange and Gibbsite also comes in white and red.
- Well-formed crystals give it away: Celestine is Orthorhombic, Gibbsite is Monoclinic.
Celestine vs Gibbsite properties
| Property | Celestine | Gibbsite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 3–3.5 | 2.5–3.5 |
| Luster | Vitreous, pearly on cleavage | Vitreous, pearly on cleavage, dull when earthy |
| Streak | White | White |
| Transparency | Transparent to translucent | Transparent to translucent |
| Specific gravity | 3.95–3.97 | 2.3–2.4 |
| Crystal system | Orthorhombic | Monoclinic |
| Common colors | Colorless, Pale blue, White, Gray, Light green, Orange (rare) | White, Gray, Greenish, Reddish |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Celestine and Gibbsite trade in a similar range, around $20.
About Celestine
Celestine, also spelled celestite, is strontium sulfate, SrSO4, and the primary ore of strontium, crystallizing in the orthorhombic system. It is best known for growing in delicate pale blue, tabular crystals, a color that gave the mineral its name from the Latin caelestis, meaning heavenly. Celestine often forms alongside gypsum and calcite in sedimentary evaporite settings, distinguishing it from most other sulfate minerals of hydrothermal origin.
About Gibbsite
Gibbsite is aluminum hydroxide, Al(OH)3, a soft, typically white to gray mineral that forms as a weathering product in tropical and subtropical soils and serves as the principal ore mineral of aluminum within bauxite deposits. It commonly occurs as fine-grained, earthy masses or crusts rather than well-formed crystals, though occasional tabular pseudohexagonal crystals do develop in cavities. It is named after American mineral collector George Gibbs, whose collection helped found early American mineralogy.
Celestine vs Gibbsite FAQ
Is Celestine the same as Gibbsite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Celestine from Gibbsite?
Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Celestine feels noticeably heavier for its size (specific gravity 3.95–3.97 versus 2.3–2.4 for Gibbsite). They overlap in gray and green, but Celestine also comes in clear, blue, and orange and Gibbsite also comes in white and red.
Which is harder, Celestine or Gibbsite?
They are about equally hard, both near Mohs 3–3.5.
Which is more valuable, Celestine or Gibbsite?
Typical specimens of Celestine and Gibbsite trade in a similar range, around $20.
