Pyrite concretions, commonly known as pyrite suns, are flat, radiating crystalline growths that form between layers of shale. They are highly sought after by collectors for their unique disc-like shape and metallic brassy luster, often found by digging in the spoil piles of old coal mines.
Is this pyrite concretions?
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 pyrite concretions with a known reference. Pyrite Concretions sits at Mohs 6-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Pyrite Concretions leaves a greenish-black streak.
- 3Read the lusterHold the specimen under a strong light. Pyrite Concretions typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: brass-yellow.
- 5Look at form & habitCrystal system: cubic. Typical habit: radial fibrous disk.
Often confused with
Pyrite Concretions vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside pyrite concretions
Minerals reported to co-occur with pyrite concretions. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeS₂
- Mohs hardness
- 6-6.5
- Density
- 4.8-5.1 g/cm³
- Colors
- Streak
- Greenish-black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Radial Fibrous Disk
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Decorative
- Host rock
- Sedimentary Shale and Coal Beds
- Typical price
- $10-150 depending on size and radial definition
Where rockhounds find pyrite concretions
3 mapped spotsClassic worldwide localities
- Sparta, Illinois
- Carbondale, Illinois
- Coal mines of the Illinois Basin
Field-hunting tip
Look in sedimentary shale and coal beds country — that is the host setting where pyrite concretions typically forms. If you start seeing shale, coal, sphalerite in float, you are in the right ground. Field specimens usually show a radial fibrous disk habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Kansas, Vermont, West Virginia — start trip planning there.
Common questions
How do you identify pyrite concretions?+
Where is pyrite concretions found?+
Can I find pyrite concretions in the United States?+
How much is pyrite concretions worth?+
What rocks look like pyrite concretions?+
What minerals are found with pyrite concretions?+
What kind of rock does pyrite concretions form in?+
What is pyrite concretions used for?+
Find pyrite concretions on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
