Ecdemite is a rare lead-arsenic oxychloride often found as yellow, waxy crusts or small, thin tabular crystals in oxidized zones of lead mines. Collectors look for its characteristic resinous luster and distinct color, though it is usually identified through chemical analysis due to its visual similarity to other secondary lead minerals.
Is this ecdemite?
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 ecdemite with a known reference. Ecdemite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ecdemite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Ecdemite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: yellow, orange, greenish-yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, crusts, massive.
Often confused with
Ecdemite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Mimetite is the harder of the two (Mohs 3.5-4 vs. 2.5); streak differs — Ecdemite leaves yellow, Mimetite leaves white; luster reads resinous on Ecdemite and adamantine on Mimetite.
How to tell apart: Streak differs — Ecdemite leaves yellow, Wulfenite leaves white.
How to tell apart: Pyromorphite is the harder of the two (Mohs 3.5-4 vs. 2.5); streak differs — Ecdemite leaves yellow, Pyromorphite leaves white.
Often found alongside ecdemite
Minerals reported to co-occur with ecdemite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₆As₂O₇Cl₄
- Mohs hardness
- 2.5
- Density
- 7.1-7.2 g/cm³
- Streak
- Yellow
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular Crystals, Crusts, Massive
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Lead-arsenic Ore Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find ecdemite
Classic worldwide localities
- Långban, Sweden
- Tsumeb, Namibia
- Tiger, Arizona, USA
Field-hunting tip
Look in oxidized lead-arsenic ore deposits country — that is the host setting where ecdemite typically forms. If you start seeing galena, mimetite, cerussite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ecdemite?+
Where is ecdemite found?+
How much is ecdemite worth?+
Is ecdemite safe to handle?+
What rocks look like ecdemite?+
What minerals are found with ecdemite?+
What kind of rock does ecdemite form in?+
What is ecdemite used for?+
Find ecdemite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
