Allargentum is a rare silver-antimony intermetallic mineral often found as intimate intergrowths with dyscrasite and native silver. Collectors should look for its distinctive bright silver-white metallic luster in hydrothermal vein deposits. It is best identified through micro-analysis as it is visually indistinguishable from other silver-antimony minerals without specialized testing.
Is this allargentum?
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 allargentum with a known reference. Allargentum sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Allargentum leaves a silver-white streak.
- 3Read the lusterHold the specimen under a strong light. Allargentum typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: silver-white, tin-white.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: massive, anhedral grains, blebs.
Often confused with
Allargentum vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside allargentum
Minerals reported to co-occur with allargentum. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₁-ₓSbₓ
- Mohs hardness
- 2.5-3
- Density
- 9.9-10.4 g/cm³
- Colors
- Streak
- Silver-white
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Massive, Anhedral Grains, Blebs
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Silver-antimony Veins
- Typical price
- $50-300 per specimen depending on rarity and associated minerals
Where rockhounds find allargentum
Classic worldwide localities
- Cobalt, Ontario, Canada
- Andreasberg, Germany
- Sala, Sweden
- Broken Hill, Australia
Field-hunting tip
Look in hydrothermal silver-antimony veins country — that is the host setting where allargentum typically forms. If you start seeing silver, dyscrasite, antimony in float, you are in the right ground. Field specimens usually show a massive, anhedral grains, blebs habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find allargentum on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
