sulfates
Wulfenite
PbMoO4
- Crystal system
- tetragonal
- Hardness
- 2.5–3 on the Mohs scale
- Lustre
- resinous
- Colour
- Orange, yellow, red, occasionally colourless
- Where it forms
- In the oxidised zone of lead deposits, as thin tabular crystals that are among the most distinctive shapes in mineralogy.
- Chiefly from
- Red Cloud Mine, Arizona, United StatesMezica, SloveniaMoroccoMexico
Why it is that colour
The lead molybdate compound; chromium impurities intensify the red.
Safety
A lead molybdate, soft and fragile. The same rules as galena and vanadinite: minimal handling, hands washed, no powdering, no water, well away from children.
Where it comes from
Arizona’s Red Cloud Mine produced the finest crystals known and is effectively worked out; the mine has been operated specifically for specimens. Moroccan and Mexican material supplies the market.
Historical use
A minor ore of molybdenum. Named after Franz Xavier von Wulfen, an eighteenth-century Jesuit mineralogist.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
Worth knowing
Wulfenite crystals are often so thin that they are effectively square wafers, sometimes under a millimetre thick and a centimetre across, standing on edge. It is one of the more improbable-looking things a mineral does, and it happens because growth in the direction perpendicular to the plate is enormously slower than growth within it.
Arizona made it the state mineral in 2017. It is also lead, which is a slightly awkward thing for a state mineral to be.
Identity checked against IMA-CNMNC master list, June 2025.