Identification guide · Oxide Minerals
How to Identify Pyrolusite
Pyrolusite is usually black, steel gray, and bluish gray with a metallic luster and is opaque. It has a Mohs hardness of 6.25. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Its streak is black to bluish black. It is most often confused with Hematite, Ilmenite, and Banded Iron Formation; the tests below separate them.
Pyrolusite identification checklist
| Color | Black, Steel gray, Bluish gray | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Metallic | Turn it under a lamp: a true metallic shine reflects like polished metal and stays opaque at thin edges. |
| Transparency | Opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 6.25 | It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. |
| Streak | Black to bluish black | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect prismatic | |
| Fracture | Uneven | |
| Specific gravity | 5 | Very heavy, metallic heft (specific gravity about 5). |
| Crystal system | Tetragonal |
Pyrolusite look-alikes and how to tell them apart
Both sit near Mohs 6.25, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Pyrolusite vs Hematite →
Both sit near Mohs 6.25, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Pyrolusite vs Ilmenite →
Both sit near Mohs 6.25, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Pyrolusite vs Banded Iron Formation →
Both sit near Mohs 6.25, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Field tips
- Look for a steel-gray to black metallic mineral that leaves a black streak and can soil the fingers.
- Massive and fibrous habits are typical, and branching black dendrites are a recognizable form.
- Soft, sooty manganese oxide coatings are commonly pyrolusite mixed with related manganese minerals.
Pyrolusite identification FAQ
How can you tell if a rock is Pyrolusite?
Check the color (black, steel gray, and bluish gray), the metallic luster, a Mohs hardness of 6.25 and a black to bluish black streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Pyrolusite?
Pyrolusite has a Mohs hardness of 6.25. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
What is the difference between Pyrolusite and Hematite?
Pyrolusite (Mohs 6.25, metallic luster) and Hematite (Mohs 6, metallic luster) look alike, but hardness, streak and heft usually separate them. See the full Pyrolusite vs Hematite comparison for a side-by-side table.
Is Pyrolusite worth anything?
Entry-level Pyrolusite specimens sell for around $5, typical collector pieces about $35, and premium examples $200 or more depending on size, quality and locality.
What color is Pyrolusite?
Pyrolusite is most often black, steel gray, and bluish gray. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
