Pyrolusite is the primary ore of manganese, frequently found as beautiful dendritic, fern-like patterns on fracture surfaces of rocks. It is characterized by its metallic luster, heavy feel, and distinctively black, powdery streak when scratched.
Is this pyrolusite?
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 pyrolusite with a known reference. Pyrolusite sits at Mohs 2-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black, bluish black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black, bluish-black, dark gray, steel gray, iron gray, bluish gray.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: dendritic, earthy, reniform.
Often confused with
Pyrolusite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Pyrolusite leaves black, bluish black, Manganite leaves reddish brown to nearly black; luster reads metallic on Pyrolusite and submetallic on Manganite.
How to tell apart: Streak differs, so Pyrolusite leaves black, bluish black, Psilomelane leaves brownish black; luster reads metallic on Pyrolusite and submetallic on Psilomelane.
How to tell apart: Streak differs, so Pyrolusite leaves black, bluish black, Hematite leaves cherry-red or reddish brown.
Often found alongside pyrolusite
Minerals reported to co-occur with pyrolusite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnO₂
- Mohs hardness
- 2-6.5
- Density
- 5.06 g/cm³
- Colors
- Streak
- Black, bluish black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Dendritic, earthy, reniform
- Cleavage
- {110}, perfect
- Rarity
- Common
- Uses
- Industrial, Collector, Ore of manganese
- Host rock
- Formed under highly oxidizing conditions in manganese-bearing hydrothermal deposits and rocks; in bogs and lakes, under shallow marine conditions; commonly an alteration product of manganite
Where rockhounds find pyrolusite
31 mapped spotsClassic worldwide localities
- Ironwood, Gogebic Co., Michigan, USA
- Leadville, Lake Co., Colorado, USA
- Lake Valley, Sierra Co., New Mexico, USA
- Artillery Mountains, Mohave Co., Arizona, USA
- Elgersburg, Friedrichroda, and Öhrenstock, near Ilmenau, Thuringia, Germany
- Eibenstock, Saxony, Germany
U.S. states with pyrolusite
Each link opens a state-specific list of mapped rockhounding spots that produce pyrolusite.
Field-hunting tip
Where it forms: Formed under highly oxidizing conditions in manganese-bearing hydrothermal deposits and rocks; in bogs and lakes, under shallow marine conditions; commonly an alteration product of manganite. If you start seeing manganite, hollandite, hausmannite in float, you are in the right ground. Typical habit: dendritic, earthy, reniform. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, California, Idaho. Start trip planning there.
More pyrolusite photos
Common questions
How do you identify pyrolusite?+
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Can I find pyrolusite in the United States?+
What rocks look like pyrolusite?+
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Find pyrolusite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
