Jalpaite is a rare silver-copper sulfide that typically appears as lead-gray to black anhedral masses within hydrothermal veins. It is most commonly found in association with acanthite and stromeyerite, often requiring X-ray diffraction or chemical analysis for positive identification due to its unremarkable appearance.
Is this jalpaite?
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 jalpaite with a known reference. Jalpaite sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Jalpaite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Jalpaite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, iron-black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: massive, anhedral grains.
Often confused with
Jalpaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Jalpaite leaves black, Stromeyerite leaves dark gray.
How to tell apart: Chalcopyrite is the harder of the two (Mohs 3.5-4 vs. 2-2.5); streak differs, so Jalpaite leaves black, Chalcopyrite leaves greenish-black.
Often found alongside jalpaite
Minerals reported to co-occur with jalpaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₃CuS₂
- Mohs hardness
- 2-2.5
- Density
- 6.83 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Massive, Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Vein Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find jalpaite
Classic worldwide localities
- Jalpa, Mexico
- Freiberg, Germany
- Guanajuato, Mexico
- Broken Hill, Australia
Field-hunting tip
Look in hydrothermal vein deposits country, the host setting where jalpaite typically forms. If you start seeing acanthite, stromeyerite, pyrite in float, you are in the right ground. Field specimens usually show a massive, anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find jalpaite on the map
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