Oxy-schorl is a relatively recently defined mineral species within the tourmaline supergroup, specifically recognized as the oxy-analogue of schorl. It typically appears as black, prismatic crystals that are macroscopically indistinguishable from common schorl without advanced analytical techniques. Collectors generally identify it by its specific geochemical context in evolved pegmatites and granitic environments.
Is this oxy-schorl?
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 oxy-schorl with a known reference. Oxy-schorl sits at Mohs 7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: greenish, brownish black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals with rounded triangular cross-sections, often striated.
Often confused with
Oxy-schorl vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Oxy-schorl leaves pale gray, Schorl leaves white.
How to tell apart: Streak differs, so Oxy-schorl leaves pale gray, Dravite leaves light brown, white.
How to tell apart: Streak differs, so Oxy-schorl leaves pale gray, Foitite leaves grayish white.
Often found alongside oxy-schorl
Minerals reported to co-occur with oxy-schorl. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(Fe²⁺₂Al)Al₆Si₆O₁₈(BO₃)₃(OH)₃O
- Mohs hardness
- 7
- Density
- 3.17-3.19 g/cm³
- Colors
- Streak
- Pale gray
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic crystals with rounded triangular cross-sections, often striated
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal fracture fillings in metasomatized rocks (Slovakia); a metasomatized primary magmatic mineral in granite, now foliated orthogneiss (Czech Republic)
Where rockhounds find oxy-schorl
Classic worldwide localities
- Czech Republic
- Germany
- Italy
- Norway
Field-hunting tip
Where it forms: Hydrothermal fracture fillings in metasomatized rocks (Slovakia); a metasomatized primary magmatic mineral in granite, now foliated orthogneiss (Czech Republic). If you start seeing orthoclase perthite, albite, quartz in float, you are in the right ground. Typical habit: prismatic crystals with rounded triangular cross-sections, often striated. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify oxy-schorl?+
Where is oxy-schorl found?+
What rocks look like oxy-schorl?+
What minerals are found with oxy-schorl?+
What kind of rock does oxy-schorl form in?+
What is oxy-schorl used for?+
Find oxy-schorl on the map
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