Grahamite is a solid, brittle bitumen that appears as black, vein-like fillings in sedimentary rocks. It is characterized by its bright, resinous-to-oily luster and a clean fracture, often mistaken for coal or jet.
Is this grahamite?
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 grahamite with a known reference. Grahamite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Grahamite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Grahamite typically shows a bright luster.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: amorphous. Typical habit: massive, vein fillings.
Often confused with
Grahamite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside grahamite
Minerals reported to co-occur with grahamite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 2
- Density
- 1.1-1.2 g/cm³
- Colors
- Streak
- Black
- Luster
- Bright
- Transparency
- Opaque
- Crystal system
- Amorphous
- Crystal habit
- Massive, Vein Fillings
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Sedimentary Veins
- Typical price
- $10-50 for typical specimens
Where rockhounds find grahamite
1 mapped spotsClassic worldwide localities
- West Virginia, USA
- Oklahoma, USA
- Cuba
- Argentina
Field-hunting tip
Look in sedimentary veins country — that is the host setting where grahamite typically forms. If you start seeing calcite, quartz in float, you are in the right ground. Field specimens usually show a massive, vein fillings habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Oklahoma — start trip planning there.
Common questions
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Find grahamite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
