Strontiomelane is a rare manganese oxide mineral belonging to the hollandite group, typically occurring as fine acicular or fibrous aggregates. It is best identified through professional analytical techniques due to its strong structural resemblance to other cryptomelane-group minerals found in manganese-rich hydrothermal veins.
Is this strontiomelane?
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 strontiomelane with a known reference. Strontiomelane sits at Mohs 4-4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: sepia.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: anhedral grains, inclusions, microscopic crystals.
Often confused with
Strontiomelane vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Hollandite is the harder of the two (Mohs 6 vs. 4-4.5); streak differs, so Strontiomelane leaves sepia, Hollandite leaves black; luster reads submetallic on Strontiomelane and metallic, splendent on Hollandite.
How to tell apart: Cryptomelane is the harder of the two (Mohs 6-6.5 vs. 4-4.5); streak differs, so Strontiomelane leaves sepia, Cryptomelane leaves brownish black; luster reads submetallic on Strontiomelane and metallic to dull on Cryptomelane.
How to tell apart: Streak differs, so Strontiomelane leaves sepia, Psilomelane leaves brownish black.
Often found alongside strontiomelane
Minerals reported to co-occur with strontiomelane. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SrMn₈O₁₆
- Mohs hardness
- 4-4.5
- Density
- 4.66 g/cm³
- Colors
- Streak
- Sepia
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Anhedral grains, inclusions, microscopic crystals
- Cleavage
- Observed, rare
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A primary mineral in meta-ophiolite rocks (amphibolite-eclogite facies), the Mn deposit originally of seafloor hydrothermal origin
Where rockhounds find strontiomelane
Classic worldwide localities
- Praborna Mn deposit,5 km south ofSaint-Marcel, Aosta Valley, Italy
Field-hunting tip
Where it forms: A primary mineral in meta-ophiolite rocks (amphibolite-eclogite facies), the Mn deposit originally of seafloor hydrothermal origin. If you start seeing braunite, hollandite, cryptomelane in float, you are in the right ground. Typical habit: anhedral grains, inclusions, microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify strontiomelane?+
Where is strontiomelane found?+
What rocks look like strontiomelane?+
What minerals are found with strontiomelane?+
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Find strontiomelane on the map
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