Sakuraiite is an extremely rare indium-bearing sulfide mineral that typically occurs as small inclusions or massive aggregates in hydrothermal tin-polymetallic deposits. It is best identified through laboratory analysis, as it is megascopically indistinguishable from other dark, metallic sulfides like sphalerite or stannite.
Is this sakuraiite?
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 sakuraiite with a known reference. Sakuraiite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: lead-gray with olive tint.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: greenish steel gray, greenish gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: exsolution inclusions, microscopic crystals.
Often confused with
Sakuraiite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Sakuraiite leaves lead-gray with olive tint, Sphalerite leaves pale brown to pale yellow and white; luster reads metallic on Sakuraiite and resinous to adamantine on Sphalerite.
How to tell apart: Streak differs, so Sakuraiite leaves lead-gray with olive tint, Stannite leaves blackish.
How to tell apart: Streak differs, so Sakuraiite leaves lead-gray with olive tint, Chalcopyrite leaves greenish black.
Often found alongside sakuraiite
Minerals reported to co-occur with sakuraiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Cu,Zn,Fe,In,Sn)₄S₄
- Mohs hardness
- 4
- Density
- 4.45 g/cm³
- Colors
- Greenish steel grayGreenish gray
- Streak
- Lead-gray with olive tint
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Exsolution inclusions, microscopic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a banded hydrothermal vein
Where rockhounds find sakuraiite
Classic worldwide localities
- Ikuno mine, Hyogo Prefecture, Japan (type locality)
Field-hunting tip
Where it forms: In a banded hydrothermal vein. If you start seeing stannite, sphalerite, chalcopyrite in float, you are in the right ground. Typical habit: exsolution inclusions, microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sakuraiite?+
Where is sakuraiite found?+
Is sakuraiite safe to handle?+
What rocks look like sakuraiite?+
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Find sakuraiite on the map
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