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, 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.
