Sadanagaite is a complex amphibole group mineral typically identified by its dark color and prismatic habit within metamorphic environments. It is chemically distinguished by high levels of aluminum and potassium substitution, often requiring analytical methods for definitive field identification. It is most frequently found as an accessory mineral in high-grade metamorphic skarn deposits.
Is this sadanagaite?
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 sadanagaite with a known reference. Sadanagaite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Sadanagaite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Sadanagaite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, dark brown, dark green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive.
Often confused with
Sadanagaite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Sadanagaite leaves white, Hornblende leaves grayish-white.
How to tell apart: Streak differs — Sadanagaite leaves white, Hastingsite leaves white to light gray.
Often found alongside sadanagaite
Minerals reported to co-occur with sadanagaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Na)Ca₂(Fe²⁺,Mg,Fe³⁺,Al)₅(Si,Al)₈O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.46 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Massive
- Cleavage
- Perfect in Two Directions At 56 and 124 Degrees
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Metamorphic Skarns and Carbonate-rich Rocks
- Typical price
- $20-150 per specimen
Where rockhounds find sadanagaite
Classic worldwide localities
- Sannae, Hyogo Prefecture, Japan
- Kola Peninsula, Russia
- Pargas, Finland
Field-hunting tip
Look in metamorphic skarns and carbonate-rich rocks country — that is the host setting where sadanagaite typically forms. If you start seeing calcite, diopside, magnetite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find sadanagaite on the map
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