Comparison · Igneous Rocks vs Quartz Family
Pumice vs Quartz
Pumice and Quartz are easy to confuse. Quartz is harder (Mohs 7) than Pumice (Mohs 5–6), so Quartz will scratch Pumice and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Pumice and Quartz
- Quartz is harder (Mohs 7) than Pumice (Mohs 5–6), so Quartz will scratch Pumice and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
- Quartz feels noticeably heavier for its size (specific gravity 2.65 versus 0.25–0.9 for Pumice).
- Hold a thin edge to the light: Pumice is Opaque, translucent in thin shards, Quartz is Transparent to translucent.
- They overlap in gray, brown, and yellow, but Pumice also comes in white and Quartz also comes in clear, purple, pink, and black.
- Well-formed crystals give it away: Pumice is Amorphous, Quartz is Trigonal.
Pumice vs Quartz properties
| Property | Pumice | Quartz |
|---|---|---|
| Type | Igneous Rocks | Quartz Family |
| Mohs hardness | 5–6 | 7 |
| Luster | Dull to glassy | Vitreous, greasy on fracture surfaces |
| Streak | — | White |
| Transparency | Opaque, translucent in thin shards | Transparent to translucent |
| Specific gravity | 0.25–0.9 | 2.65 |
| Crystal system | Amorphous | Trigonal |
| Common colors | White, Light gray, Tan, Pale yellow | Colorless, White, Purple (amethyst), Yellow (citrine), Pink (rose), Brown/black (smoky) |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $5–$250+ |
Which is more valuable?
Quartz is usually the more valuable of the two: a typical collector specimen runs about $35 against $10 for Pumice, and premium Quartz can reach $250 or more.
About Pumice
Pumice is a light-colored, extrusive volcanic rock so full of trapped gas bubbles, or vesicles, that it can float on water. It forms when gas-rich, silica-rich magma is violently depressurized during an explosive eruption, freezing the expanding bubbles in place as volcanic glass. Its extremely low density and rough, abrasive texture have made it useful to people for thousands of years.
About Quartz
Quartz is silicon dioxide, SiO2, one of the most abundant minerals in Earth's continental crust, crystallizing in the trigonal division of the hexagonal crystal system with a hardness of 7 that makes it a standard reference point on the Mohs scale. Its six-sided prismatic crystals, often terminated by pyramidal points, are among the most recognizable crystal shapes in mineralogy. Quartz occurs in nearly every rock type and geologic setting, from granite pegmatites to sedimentary sandstones to hydrothermal veins.
Pumice vs Quartz FAQ
Is Pumice the same as Quartz?
No. Pumice is a igneous rock while Quartz is a quartz family. Quartz is harder (Mohs 7) than Pumice (Mohs 5–6), so Quartz will scratch Pumice and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
How can you tell Pumice from Quartz?
Quartz is harder (Mohs 7) than Pumice (Mohs 5–6), so Quartz will scratch Pumice and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Quartz feels noticeably heavier for its size (specific gravity 2.65 versus 0.25–0.9 for Pumice). Hold a thin edge to the light: Pumice is Opaque, translucent in thin shards, Quartz is Transparent to translucent.
Which is harder, Pumice or Quartz?
Quartz is harder: Mohs 7 against Mohs 5–6 for Pumice.
Which is more valuable, Pumice or Quartz?
Quartz is usually the more valuable of the two: a typical collector specimen runs about $35 against $10 for Pumice, and premium Quartz can reach $250 or more.
