Comparison · Minerals vs Feldspar Group
Apophyllite vs Feldspar
Apophyllite and Feldspar are easy to confuse. Feldspar is harder (Mohs 6–6.5) than Apophyllite (Mohs 4.5–5), so Feldspar will scratch Apophyllite 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 Apophyllite and Feldspar
- Feldspar is harder (Mohs 6–6.5) than Apophyllite (Mohs 4.5–5), so Feldspar will scratch Apophyllite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
- They overlap in clear, green, and pink, but Apophyllite also comes in yellow and Feldspar also comes in gray.
- Well-formed crystals give it away: Apophyllite is Tetragonal, Feldspar is Monoclinic to Triclinic (depending on species).
Apophyllite vs Feldspar properties
| Property | Apophyllite | Feldspar |
|---|---|---|
| Type | Minerals | Feldspar Group |
| Mohs hardness | 4.5–5 | 6–6.5 |
| Luster | Vitreous, pearly on cleavage | Vitreous to pearly |
| Streak | White | White |
| Transparency | Transparent to translucent | Transparent to translucent |
| Specific gravity | 2.3–2.4 | 2.55–2.76 |
| Crystal system | Tetragonal | Monoclinic to Triclinic (depending on species) |
| Common colors | Colorless, White, Green, Pink, Pale yellow | White, Pink, Gray, Green (amazonite), Colorless |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Apophyllite and Feldspar trade in a similar range, around $20.
About Apophyllite
Apophyllite is the common name for a small group of hydrated potassium calcium silicates, most often KCa4Si8O20(F,OH)·8H2O, crystallizing in the tetragonal system. It typically grows as glassy, pseudo-cubic or pyramidal crystals lining cavities in basaltic lava. The name comes from the Greek for 'to leaf away,' describing how the mineral flakes when heated, losing its water of crystallization.
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.
Apophyllite vs Feldspar FAQ
Is Apophyllite the same as Feldspar?
No. Apophyllite is a mineral while Feldspar is a feldspar group. Feldspar is harder (Mohs 6–6.5) than Apophyllite (Mohs 4.5–5), so Feldspar will scratch Apophyllite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
How can you tell Apophyllite from Feldspar?
Feldspar is harder (Mohs 6–6.5) than Apophyllite (Mohs 4.5–5), so Feldspar will scratch Apophyllite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. They overlap in clear, green, and pink, but Apophyllite also comes in yellow and Feldspar also comes in gray. Well-formed crystals give it away: Apophyllite is Tetragonal, Feldspar is Monoclinic to Triclinic (depending on species).
Which is harder, Apophyllite or Feldspar?
Feldspar is harder: Mohs 6–6.5 against Mohs 4.5–5 for Apophyllite.
Which is more valuable, Apophyllite or Feldspar?
Typical specimens of Apophyllite and Feldspar trade in a similar range, around $20.
