Shigaite is a rare hydrated sulfate mineral that typically forms vibrant, honey-yellow hexagonal plates or rosettes. It is most famous among collectors for specimens found in the manganese mines of Japan and the rare mineral-rich alkaline rocks of Mont Saint-Hilaire, Canada. Collectors should handle these specimens with care, as the mineral is prone to dehydration and damage due to its high water content.
Is this shigaite?
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 shigaite with a known reference. Shigaite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Shigaite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Shigaite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, golden yellow, orange yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: tabular crystals, hexagonal plates, rosettes.
Often confused with
Shigaite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside shigaite
Minerals reported to co-occur with shigaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaAl₃(Mn²⁺,Mg,Fe²⁺)₆(SO₄)₂(OH)₁₂·12H₂O
- Mohs hardness
- 2.5
- Density
- 2.05 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Tabular Crystals, Hexagonal Plates, Rosettes
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Manganese Deposits and Alkaline Igneous Complexes
- Typical price
- $50-300 depending on specimen size and clarity
Where rockhounds find shigaite
Classic worldwide localities
- Shiga Prefecture, Japan
- Mont Saint-Hilaire, Quebec, Canada
- Kalahari Manganese Fields, South Africa
Field-hunting tip
Look in metamorphic manganese deposits and alkaline igneous complexes country, the host setting where shigaite typically forms. If you start seeing rhodochrosite, hausmannite, manganite in float, you are in the right ground. Field specimens usually show a tabular crystals, hexagonal plates, rosettes habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find shigaite on the map
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