Comparison · Sedimentary Rocks vs Quartz Family
Flint vs Smoky Quartz
Flint and Smoky Quartz are easy to confuse. Both sit near Mohs 6.5–7, 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 Flint and Smoky Quartz
- Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Hold a thin edge to the light: Flint is Translucent at thin edges to opaque, Smoky Quartz is transparent.
Flint vs Smoky Quartz properties
| Property | Flint | Smoky Quartz |
|---|---|---|
| Type | Sedimentary Rocks | Quartz Family |
| Mohs hardness | 6.5–7 | 7 |
| Luster | Waxy to dull, glassy on fresh fracture | vitreous |
| Streak | — | White |
| Transparency | Translucent at thin edges to opaque | transparent |
| Specific gravity | 2.6–2.65 | 2.65 |
| Crystal system | — | hexagonal |
| Common colors | Black, Dark gray, Brown | Brown, Gray, Black |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $5–$150+ |
Which is more valuable?
Smoky Quartz is usually the more valuable of the two: a typical collector specimen runs about $30 against $10 for Flint, and premium Smoky Quartz can reach $150 or more.
About Flint
Flint is a dense, dark variety of chert composed of microcrystalline quartz, most classically known from nodules embedded within the chalk deposits of northern Europe. Chemically and structurally identical to chert, flint is distinguished mainly by its typically dark gray to black color and its strong association with chalk host rock, along with its long cultural history as a toolmaking material. Its conchoidal fracture produces razor-sharp edges, a property exploited by humans for well over two million years.
About Smoky Quartz
Smoky quartz is a brown to black variety of quartz colored by natural irradiation. The national gem of Scotland, it ranges from light tan to nearly opaque black.
Flint vs Smoky Quartz FAQ
Is Flint the same as Smoky Quartz?
No. Flint is a sedimentary rock while Smoky Quartz is a quartz family. Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Flint from Smoky Quartz?
Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Hold a thin edge to the light: Flint is Translucent at thin edges to opaque, Smoky Quartz is transparent.
Which is harder, Flint or Smoky Quartz?
They are about equally hard, both near Mohs 6.5–7.
Which is more valuable, Flint or Smoky Quartz?
Smoky Quartz is usually the more valuable of the two: a typical collector specimen runs about $30 against $10 for Flint, and premium Smoky Quartz can reach $150 or more.
