Comparison · Minerals vs Feldspar Group
Dioptase vs Feldspar
Dioptase and Feldspar are easy to confuse. Feldspar is harder (Mohs 6–6.5) than Dioptase (Mohs 5), so Feldspar will scratch Dioptase and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Dioptase and Feldspar
- Feldspar is harder (Mohs 6–6.5) than Dioptase (Mohs 5), so Feldspar will scratch Dioptase and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
- Streak color differs: Dioptase leaves a green streak on unglazed porcelain, Feldspar leaves white.
- Dioptase feels noticeably heavier for its size (specific gravity 3.28–3.35 versus 2.55–2.76 for Feldspar).
- They overlap in green, but Feldspar also comes in pink, gray, and clear.
- Well-formed crystals give it away: Dioptase is Trigonal, Feldspar is Monoclinic to Triclinic (depending on species).
Dioptase vs Feldspar properties
| Property | Dioptase | Feldspar |
|---|---|---|
| Type | Minerals | Feldspar Group |
| Mohs hardness | 5 | 6–6.5 |
| Luster | Vitreous | Vitreous to pearly |
| Streak | Green | White |
| Transparency | Transparent to translucent | Transparent to translucent |
| Specific gravity | 3.28–3.35 | 2.55–2.76 |
| Crystal system | Trigonal | Monoclinic to Triclinic (depending on species) |
| Common colors | Emerald green, Bluish green | White, Pink, Gray, Green (amazonite), Colorless |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Dioptase and Feldspar trade in a similar range, around $20.
About Dioptase
Dioptase is a copper cyclosilicate mineral, Cu6Si6O18·6H2O, prized for an intense emerald-green color that rivals fine emerald despite being a completely different mineral species. It forms in the oxidized zones of copper ore deposits under arid conditions, typically as small but brilliantly lustrous crystals. Dioptase is too soft and brittle to be widely used as a gemstone, so its value lies almost entirely with mineral collectors.
About Feldspar
Feldspar is not a single mineral but a group of related aluminosilicate minerals, comprising the potassium feldspars, orthoclase, microcline, and sanidine, and the plagioclase series running from albite to anorthite, together making up roughly 60 percent of Earth's crust by volume. All share a similar framework silicate structure, two cleavage directions near 90 degrees, and moderate hardness, but differ in composition, color, and crystal system. As the most abundant mineral group on the planet, feldspar defines granite, basalt, gneiss, and countless other rock types.
Dioptase vs Feldspar FAQ
Is Dioptase the same as Feldspar?
No. Dioptase is a mineral while Feldspar is a feldspar group. Feldspar is harder (Mohs 6–6.5) than Dioptase (Mohs 5), so Feldspar will scratch Dioptase and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
How can you tell Dioptase from Feldspar?
Feldspar is harder (Mohs 6–6.5) than Dioptase (Mohs 5), so Feldspar will scratch Dioptase and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Streak color differs: Dioptase leaves a green streak on unglazed porcelain, Feldspar leaves white. Dioptase feels noticeably heavier for its size (specific gravity 3.28–3.35 versus 2.55–2.76 for Feldspar).
Which is harder, Dioptase or Feldspar?
Feldspar is harder: Mohs 6–6.5 against Mohs 5 for Dioptase.
Which is more valuable, Dioptase or Feldspar?
Typical specimens of Dioptase and Feldspar trade in a similar range, around $20.
