Fedorovskite is a rare magnesium-calcium borate mineral typically found in metamorphic skarn deposits. Collectors prize it for its association with other borate minerals, appearing most often as white to colorless granular masses within rock matrices.
Is this fedorovskite?
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 fedorovskite with a known reference. Fedorovskite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: granular aggregates, massive, sometimes as small crystals in cavities.
Often confused with
Fedorovskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Sinhalite is the harder of the two (Mohs 6.5-7 vs. 4.5); streak differs, so Fedorovskite leaves brownish, Sinhalite leaves white.
How to tell apart: Streak differs, so Fedorovskite leaves brownish, Ludwigite leaves black to greenish black; luster reads vitreous on Fedorovskite and submetallic on Ludwigite.
How to tell apart: Suanite is the harder of the two (Mohs 5.5 vs. 4.5); streak differs, so Fedorovskite leaves brownish, Suanite leaves white; luster reads vitreous on Fedorovskite and silky to pearly on Suanite.
Often found alongside fedorovskite
Minerals reported to co-occur with fedorovskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Mg₂B₄O₇(OH)₆
- Mohs hardness
- 4.5
- Density
- 2.65 g/cm³
- Colors
- Streak
- Brownish
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Granular aggregates, massive, sometimes as small crystals in cavities
- Cleavage
- On {100}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In veinlets in a skarn-type boron deposit
Where rockhounds find fedorovskite
Classic worldwide localities
- Solongo boron deposit, Buryatia, Transbaikal region, Russia
Field-hunting tip
Where it forms: In veinlets in a skarn-type boron deposit. If you start seeing sakhaite, frolovite, uralborite in float, you are in the right ground. Typical habit: granular aggregates, massive, sometimes as small crystals in cavities. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fedorovskite?+
Where is fedorovskite found?+
What rocks look like fedorovskite?+
What minerals are found with fedorovskite?+
What kind of rock does fedorovskite form in?+
What is fedorovskite used for?+
Find fedorovskite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
