Niigataite is a strontium-rich member of the clinozoisite-epidote group, uniquely identified by its distinctive pink coloration caused by its composition. It is primarily found as an accessory mineral in high-pressure, low-temperature metamorphic rocks in Japan. Collectors look for its well-formed prismatic crystals embedded in quartz or schist matrices.
Is this niigataite?
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 niigataite with a known reference. Niigataite sits at Mohs 6-7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pink, reddish-pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial aggregates, massive.
Often confused with
Niigataite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Niigataite leaves white, Clinozoisite leaves grayish white.
How to tell apart: Streak differs, so Niigataite leaves white, Epidote leaves grayish white.
How to tell apart: Streak differs, so Niigataite leaves white, Piemontite leaves reddish.
Often found alongside niigataite
Minerals reported to co-occur with niigataite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSrAl₃(Si₂O₇)(SiO₄)O(OH)
- Mohs hardness
- 6-7
- Colors
- PinkReddish-pink
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, radial aggregates, massive
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- metamorphic rocks
Where rockhounds find niigataite
Classic worldwide localities
- Niigata Prefecture, Japan
- Kochi Prefecture, Japan
Field-hunting tip
Where it forms: metamorphic rocks. If you start seeing quartz, albite, calcite in float, you are in the right ground. Typical habit: prismatic crystals, radial aggregates, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify niigataite?+
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What rocks look like niigataite?+
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Find niigataite on the map
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