Krettnichite is a very rare secondary mineral member of the Tsumcorite group, typically found as small tabular crystals or thin crusts in oxidized mineral deposits. It is chemically notable for its manganese content and is highly sought after by advanced mineral collectors for its limited type locality occurrences.
Is this krettnichite?
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 krettnichite with a known reference. Krettnichite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Krettnichite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Krettnichite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: yellow, brownish-yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, drusy crusts.
Often confused with
Krettnichite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Tsumcorite is the harder of the two (Mohs 4.5 vs. 3.5); streak differs — Krettnichite leaves yellow, Tsumcorite leaves yellowish; luster reads adamantine on Krettnichite and vitreous on Tsumcorite.
How to tell apart: Krettnichite is noticeably harder (Mohs 3.5 vs. 2); luster reads adamantine on Krettnichite and vitreous on Helmutwinklerite.
Often found alongside krettnichite
Minerals reported to co-occur with krettnichite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbMn³⁺₂(AsO₄)₂(OH)₂
- Mohs hardness
- 3.5
- Density
- 5.72 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Drusy Crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Hydrothermal Lead-arsenic Deposits
- Typical price
- $50-300 per thumbnail
Where rockhounds find krettnichite
Classic worldwide localities
- Krettnich, Germany
- Tsumeb, Namibia
Field-hunting tip
Look in oxidized hydrothermal lead-arsenic deposits country — that is the host setting where krettnichite typically forms. If you start seeing mimetite, goethite, quartz in float, you are in the right ground. Field specimens usually show a tabular crystals, drusy crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find krettnichite on the map
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