Pseudolyonsite is an extremely rare copper iron vanadate that typically forms as small, yellow, tabular crystals or crusts within volcanic fumaroles. It is primarily known from the Izalco Volcano in El Salvador, where it occurs as a sublimate from hot volcanic gases.
Is this pseudolyonsite?
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 pseudolyonsite with a known reference. Pseudolyonsite 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. Streak: reddish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine to semi-metallic.
- 4Match the color rangeCompare against the expected color range: dark red with brownish tint.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, crusts.
Often confused with
Pseudolyonsite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside pseudolyonsite
Minerals reported to co-occur with pseudolyonsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₃(VO₄)₂
- Mohs hardness
- 2-3
- Density
- 4.749 g/cm³
- Colors
- Dark red with brownish tint
- Streak
- Reddish brown
- Luster
- Adamantine to semi-metallic
- Transparency
- Translucent to opaque
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals, crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed by late post-eruptive degassing in cavities from several centimeters to 1.5 m in size under the surface crust of volcanic cinder - typically as overgrowths on acicular piypite
Where rockhounds find pseudolyonsite
Classic worldwide localities
- Yadovitaya (‘‘Poisonous’’) fumarole, Second cone, Tolbachik volcano, Kamchatka Peninsula, Far East Asia, Russia
Field-hunting tip
Where it forms: Formed by late post-eruptive degassing in cavities from several centimeters to 1.5 m in size under the surface crust of volcanic cinder - typically as overgrowths on acicular piypite. If you start seeing piypite, palmierite, lyonsite in float, you are in the right ground. Typical habit: tabular crystals, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify pseudolyonsite?+
Where is pseudolyonsite found?+
Is pseudolyonsite safe to handle?+
What rocks look like pseudolyonsite?+
What minerals are found with pseudolyonsite?+
What kind of rock does pseudolyonsite form in?+
What is pseudolyonsite used for?+
Find pseudolyonsite on the map
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