Comparison · Feldspar Group vs Silicate Minerals
Feldspar vs Nepheline
Feldspar and Nepheline are easy to confuse. Both sit near Mohs 6–6.5, 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 Feldspar and Nepheline
- Both sit near Mohs 6–6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Hold a thin edge to the light: Feldspar is Transparent to translucent, Nepheline is translucent.
- They overlap in gray, green, and clear, but Feldspar also comes in pink and Nepheline also comes in yellow and red.
- Well-formed crystals give it away: Feldspar is Monoclinic to Triclinic (depending on species), Nepheline is hexagonal.
Feldspar vs Nepheline properties
| Property | Feldspar | Nepheline |
|---|---|---|
| Type | Feldspar Group | Silicate Minerals |
| Mohs hardness | 6–6.5 | 6 |
| Luster | Vitreous to pearly | vitreous |
| Streak | White | White |
| Transparency | Transparent to translucent | translucent |
| Specific gravity | 2.55–2.76 | 2.6 |
| Crystal system | Monoclinic to Triclinic (depending on species) | hexagonal |
| Common colors | White, Pink, Gray, Green (amazonite), Colorless | Colorless, White, Gray, Yellowish, Greenish, Reddish |
| Rarity | common | uncommon |
| Typical specimen value | $2–$150+ | $5–$150+ |
Which is more valuable?
Nepheline is usually the more valuable of the two: a typical collector specimen runs about $30 against $20 for Feldspar, and premium Nepheline can reach $150 or more.
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.
About Nepheline
Nepheline is a sodium and potassium aluminosilicate of the feldspathoid group, found in silica-poor igneous rocks. It usually appears as gray, greasy-looking masses and grains rather than well-formed crystals.
Feldspar vs Nepheline FAQ
Is Feldspar the same as Nepheline?
No. Feldspar is a feldspar group while Nepheline is a silicate mineral. Both sit near Mohs 6–6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Feldspar from Nepheline?
Both sit near Mohs 6–6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Hold a thin edge to the light: Feldspar is Transparent to translucent, Nepheline is translucent. They overlap in gray, green, and clear, but Feldspar also comes in pink and Nepheline also comes in yellow and red.
Which is harder, Feldspar or Nepheline?
They are about equally hard, both near Mohs 6–6.5.
Which is more valuable, Feldspar or Nepheline?
Nepheline is usually the more valuable of the two: a typical collector specimen runs about $30 against $20 for Feldspar, and premium Nepheline can reach $150 or more.
