Comparison · Igneous Rocks vs Quartz Family
Dacite vs Quartz
Dacite and Quartz are easy to confuse. Both sit near Mohs 6–7, 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 Dacite and Quartz
- Both sit near Mohs 6–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Hold a thin edge to the light: Dacite is Opaque, Quartz is Transparent to translucent.
- They overlap in gray and brown, but Quartz also comes in clear, purple, yellow, pink, and black.
Dacite vs Quartz properties
| Property | Dacite | Quartz |
|---|---|---|
| Type | Igneous Rocks | Quartz Family |
| Mohs hardness | 6–7 | 7 |
| Luster | Dull to vitreous | Vitreous, greasy on fracture surfaces |
| Streak | — | White |
| Transparency | Opaque | Transparent to translucent |
| Specific gravity | 2.6–2.7 | 2.65 |
| Crystal system | — | Trigonal |
| Common colors | Gray, Light gray, Tan, Pale brown | 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 Dacite, and premium Quartz can reach $250 or more.
About Dacite
Dacite is a fine-grained, extrusive igneous rock of intermediate to felsic composition, chemically positioned between andesite and rhyolite with roughly 63 to 68 percent silica. It usually shows a porphyritic texture, with visible crystals of plagioclase, quartz, and hornblende or biotite set in a dense, glassy to microcrystalline groundmass. Dacite magma is typically thick and gas-rich, making it prone to explosive eruption.
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.
Dacite vs Quartz FAQ
Is Dacite the same as Quartz?
No. Dacite is a igneous rock while Quartz is a quartz family. Both sit near Mohs 6–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Dacite from Quartz?
Both sit near Mohs 6–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Hold a thin edge to the light: Dacite is Opaque, Quartz is Transparent to translucent. They overlap in gray and brown, but Quartz also comes in clear, purple, yellow, pink, and black.
Which is harder, Dacite or Quartz?
Quartz is harder: Mohs 7 against Mohs 6–7 for Dacite.
Which is more valuable, Dacite or Quartz?
Quartz is usually the more valuable of the two: a typical collector specimen runs about $35 against $10 for Dacite, and premium Quartz can reach $250 or more.
