Derriksite is an extremely rare secondary copper uranyl selenite mineral typically found as small, vibrant emerald-green platy crystals. It occurs primarily in the oxidation zones of uranium deposits where selenium is present. Due to its scarcity and radioactivity, it is highly sought after by advanced systematic mineral collectors.
Is this derriksite?
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 derriksite with a known reference. Derriksite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Derriksite leaves a pale green streak.
- 3Read the lusterHold the specimen under a strong light. Derriksite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: emerald-green, grass-green.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: platy crystals, crusts, tabular.
Often confused with
Derriksite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Derriksite leaves pale green, Malachite leaves light green; luster reads adamantine on Derriksite and vitreous on Malachite.
How to tell apart: Luster reads adamantine on Derriksite and vitreous on Chalcophyllite.
Often found alongside derriksite
Minerals reported to co-occur with derriksite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₄(UO₂)(SeO₃)₂(OH)₆
- Mohs hardness
- 2-3
- Density
- 4.87 g/cm³
- Colors
- Streak
- Pale Green
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Platy Crystals, Crusts, Tabular
- Cleavage
- Perfect On {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Uranium-selenium Deposits
- Typical price
- $100-500 per specimen
Where rockhounds find derriksite
Classic worldwide localities
- Musonoi Mine, Democratic Republic of the Congo
- Eureka Mine, Spain
Field-hunting tip
Look in oxidized uranium-selenium deposits country — that is the host setting where derriksite typically forms. If you start seeing guilleminite, cuprite, malachite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, tabular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find derriksite on the map
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