Comparison · Feldspar Group vs Igneous Rocks
Feldspar vs Kimberlite
Feldspar and Kimberlite 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 Kimberlite
- 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, Kimberlite is Opaque.
- They overlap in gray and green, but Feldspar also comes in pink and clear and Kimberlite also comes in blue and yellow.
Feldspar vs Kimberlite properties
| Property | Feldspar | Kimberlite |
|---|---|---|
| Type | Feldspar Group | Igneous Rocks |
| Mohs hardness | 6–6.5 | 5–6.5 |
| Luster | Vitreous to pearly | Dull to vitreous |
| Streak | White | — |
| Transparency | Transparent to translucent | Opaque |
| Specific gravity | 2.55–2.76 | 2.5–2.9 |
| Crystal system | Monoclinic to Triclinic (depending on species) | — |
| Common colors | White, Pink, Gray, Green (amazonite), Colorless | Blue-gray ('blue ground'), Yellow ('yellow ground', weathered), Dark green, Gray |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $1–$75+ |
Which is more valuable?
Feldspar is usually the more valuable of the two: a typical collector specimen runs about $20 against $10 for Kimberlite, and premium Feldspar 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 Kimberlite
Kimberlite is a rare, ultramafic igneous rock famous as the primary source rock for natural diamonds. It originates from partial melting deep in Earth's mantle, often more than one hundred fifty kilometers down, and erupts violently through narrow, carrot-shaped volcanic pipes. Named after Kimberley, South Africa, where major diamond-bearing pipes were first mined, it is a chaotic mixture of olivine, mica, and fragments picked up from surrounding rock on its way to the surface.
Feldspar vs Kimberlite FAQ
Is Feldspar the same as Kimberlite?
No. Feldspar is a feldspar group while Kimberlite is a igneous rock. 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 Kimberlite?
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, Kimberlite is Opaque. They overlap in gray and green, but Feldspar also comes in pink and clear and Kimberlite also comes in blue and yellow.
Which is harder, Feldspar or Kimberlite?
Feldspar is harder: Mohs 6–6.5 against Mohs 5–6.5 for Kimberlite.
Which is more valuable, Feldspar or Kimberlite?
Feldspar is usually the more valuable of the two: a typical collector specimen runs about $20 against $10 for Kimberlite, and premium Feldspar can reach $150 or more.
