Emmerichite is a very rare member of the mica group found primarily in volcanic ejecta of the Eifel region in Germany. It typically presents as small, yellow to brown platy crystals that are difficult to distinguish from other mica species without sophisticated mineralogical analysis.
Is this emmerichite?
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 emmerichite with a known reference. Emmerichite sits at Mohs 3-4, 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: brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals.
Often confused with
Emmerichite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Emmerichite and splendent to submetallic, vitreous, pearly on cleavage on Biotite.
How to tell apart: Luster reads vitreous on Emmerichite and pearly to submetallic on cleavage on Phlogopite.
Often found alongside emmerichite
Minerals reported to co-occur with emmerichite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba₂Ti₂Na₃Fe(Si₂O₇)₂O₂F₂
- Mohs hardness
- 3-4
- Density
- 3.864 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy crystals
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A high-temperature pneumatolitic mineral in cavities within alkaline basalt
Where rockhounds find emmerichite
Classic worldwide localities
- Rother Kopf (near Roth) and Graulay (near Hillesheim) quarries, Eifel Mountains, Rheinland-Palatinate, Germany
Field-hunting tip
Where it forms: A high-temperature pneumatolitic mineral in cavities within alkaline basalt. If you start seeing nepheline, leucite, augite in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify emmerichite?+
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What rocks look like emmerichite?+
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Find emmerichite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
