Flint is a microcrystalline variety of quartz that occurs as nodules within chalk and limestone formations. It is well known for its conchoidal fracture, which produces razor-sharp edges and was historically used for tools and ignition.
Is this dark gray flint?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch dark gray flint with a known reference. Dark Gray Flint sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Dark Gray Flint leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Dark Gray Flint typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: dark gray, black, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive.
Often confused with
Dark Gray Flint vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside dark gray flint
Minerals reported to co-occur with dark gray flint. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 6.5-7
- Density
- 2.6 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Knapping, Collector
- Host rock
- Sedimentary
- Typical price
- $5-30 specimen
Where rockhounds find dark gray flint
1 mapped spotsClassic worldwide localities
- United Kingdom
- France
- Belgium
- Denmark
- Poland
Field-hunting tip
Look in sedimentary country — that is the host setting where dark gray flint typically forms. If you start seeing calcite, chalk, dolomite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Ohio — start trip planning there.
Common questions
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Find dark gray flint on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
