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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: waxy.
- 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
Where rockhounds find dark gray flint
1 mapped spotsClassic worldwide localities
- United Kingdom
- France
- Belgium
- Denmark
- Poland
Field-hunting tip
Where it forms: sedimentary. If you start seeing calcite, chalk, dolomite in float, you are in the right ground. Typical habit: massive. 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.
More dark gray flint photos
Common questions
How do you identify dark gray flint?+
Where is dark gray flint found?+
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What rocks look like dark gray flint?+
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Find dark gray flint on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
