Polhemusite is an extremely rare zinc-mercury sulfide mineral typically found in low-temperature hydrothermal deposits. It is best identified by its association with mercury minerals and its characteristic occurrence as minute, metallic, tetragonal tabular crystals.
Is this polhemusite?
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 polhemusite with a known reference. Polhemusite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous to adamantine.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, massive.
Often confused with
Polhemusite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Polhemusite leaves white, Sphalerite leaves pale brown to pale yellow and white.
How to tell apart: Polhemusite is noticeably harder (Mohs 4.5 vs. 2-2.5); streak differs, so Polhemusite leaves white, Cinnabar leaves scarlet; luster reads resinous to adamantine on Polhemusite and adamantine, inclining to metallic when dark; dull in friable material on Cinnabar.
Often found alongside polhemusite
Minerals reported to co-occur with polhemusite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Zn,Hg)S
- Mohs hardness
- 4.5
- Density
- 4.93 g/cm³
- Colors
- Streak
- White
- Luster
- Resinous to adamantine
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Tabular crystals, massive
- Cleavage
- Rare
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As part of a replacement deposit of stibnite (B and B deposit, Idaho, USA)
Where rockhounds find polhemusite
Classic worldwide localities
- B and B deposit, Big Creek district, Valley Co., Idaho (type locality), and in the Getchell mine, Potosi district, Humboldt Co., Nevada, USA
Field-hunting tip
Where it forms: As part of a replacement deposit of stibnite (B and B deposit, Idaho, USA). If you start seeing stibnite, cinnabar, mercurian sphalerite in float, you are in the right ground. Typical habit: tabular crystals, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify polhemusite?+
Where is polhemusite found?+
Is polhemusite safe to handle?+
What rocks look like polhemusite?+
What minerals are found with polhemusite?+
What kind of rock does polhemusite form in?+
What is polhemusite used for?+
Find polhemusite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
