Heidornite is a rare borate-sulfate mineral typically found in marine evaporite sequences. It usually forms small, colorless to white prismatic crystals and is primarily a target for advanced systematic mineral collectors specializing in borate species.
Is this heidornite?
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 heidornite with a known reference. Heidornite 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: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, sometimes tabular.
Often confused with
Heidornite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside heidornite
Minerals reported to co-occur with heidornite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Ca₃Cl(SO₄)₂B₅O₈(OH)₂
- Mohs hardness
- 4-5
- Density
- 2.753 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, sometimes tabular
- Cleavage
- {001}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Very rare, in a cavity in a marine evaporite deposit
Where rockhounds find heidornite
Classic worldwide localities
- Frenswegen, northwest of Nordhorn, Lower Saxony, Germany
Field-hunting tip
Where it forms: Very rare, in a cavity in a marine evaporite deposit. If you start seeing glauberite, anhydrite in float, you are in the right ground. Typical habit: prismatic crystals, sometimes tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify heidornite?+
Where is heidornite found?+
What rocks look like heidornite?+
What minerals are found with heidornite?+
What kind of rock does heidornite form in?+
What is heidornite used for?+
Find heidornite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
