Itoigawaite is a rare strontium-rich member of the lawsonite group, first discovered in the jade-bearing regions of Japan. It typically occurs as fine-grained, blue to colorless aggregates associated with jadeite deposits in serpentinite environments.
Is this itoigawaite?
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 itoigawaite with a known reference. Itoigawaite sits at Mohs 5-5.5, 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: blue.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: microscopic crystals, tabular.
Often confused with
Itoigawaite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside itoigawaite
Minerals reported to co-occur with itoigawaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SrAl₂Si₂O₇(OH)₂·H₂O
- Mohs hardness
- 5-5.5
- Density
- 3.37 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Microscopic crystals, tabular
- Cleavage
- Good in one direction
- Rarity
- Rare
- Uses
- Collector, Lapidary
- Host rock
- Product of late-stage high-P/T metamorphism, in a thin veinlet cutting a lavender-colored Ti-bearing jadeitite boulder in a river cutting serpentinite melange
Where rockhounds find itoigawaite
Classic worldwide localities
- On the seashore of Oyashirazu, about 15 km WSW of Itoigawa Station, Itoigawa-Ohmi district, Niigata-ken Prefecture, Japan (type locality)
Field-hunting tip
Where it forms: Product of late-stage high-P/T metamorphism, in a thin veinlet cutting a lavender-colored Ti-bearing jadeitite boulder in a river cutting serpentinite melange. If you start seeing jadeite, natrolite, sr-bearing pectolite in float, you are in the right ground. Typical habit: microscopic crystals, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify itoigawaite?+
Where is itoigawaite found?+
What rocks look like itoigawaite?+
What minerals are found with itoigawaite?+
What kind of rock does itoigawaite form in?+
What is itoigawaite used for?+
Find itoigawaite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
