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 3.5-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Sakuraiite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Sakuraiite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: gray, black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: massive, granular.
Often confused with
Sakuraiite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Sakuraiite leaves black, Sphalerite leaves white to yellow-brown; luster reads metallic on Sakuraiite and resinous to submetallic on Sphalerite.
How to tell apart: Streak differs — Sakuraiite leaves black, 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
- 3.5-4
- Density
- 4.5-4.8 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Massive, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find sakuraiite
Classic worldwide localities
- Ikuno mine, Japan
- Toyoha mine, Japan
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where sakuraiite typically forms. If you start seeing cassiterite, sphalerite, chalcopyrite in float, you are in the right ground. Field specimens usually show a massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find sakuraiite on the map
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