Hydrozincite is a secondary zinc mineral commonly found as earthy or botryoidal crusts in the oxidized zones of zinc deposits. It is most easily identified by its characteristic bright blue fluorescence under shortwave UV light, which helps distinguish it from similar-looking white carbonate minerals.
Is this hydrozincite?
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 hydrozincite with a known reference. Hydrozincite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly, silky to dull or earthy in aggregates.
- 4Match the color rangeCompare against the expected color range: white, yellowish white, grayish white, pinkish white, bluish white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed, massive, stalactitic.
Often confused with
Hydrozincite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Smithsonite is the harder of the two (Mohs 4-4.5 vs. 2-2.5); luster reads pearly, silky to dull or earthy in aggregates on Hydrozincite and vitreous, may be pearly on Smithsonite.
How to tell apart: Luster reads pearly, silky to dull or earthy in aggregates on Hydrozincite and adamantine, tending toward vitreous, resinous on Cerussite.
How to tell apart: Hemimorphite is the harder of the two (Mohs 4.5-5 vs. 2-2.5); luster reads pearly, silky to dull or earthy in aggregates on Hydrozincite and vitreous, subpearly, adamantine, rarely silky on Hemimorphite.
Often found alongside hydrozincite
Minerals reported to co-occur with hydrozincite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Zn₅(CO₃)₂(OH)₆
- Mohs hardness
- 2-2.5
- Density
- 4.00 g/cm³
- Streak
- White
- Luster
- Pearly, silky to dull or earthy in aggregates
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Bladed, massive, stalactitic
- Cleavage
- On {100}, perfect
- Fluorescence
- Blue white under SW and LW UV
- Rarity
- Common
- Uses
- Collector, Ore of zinc
- Host rock
- Uncommonly formed in the oxidized portions of zinc-bearing deposits, at the expense of sphalerite or smithsonite, and as incrustations in mine workings and caves
Where rockhounds find hydrozincite
4 mapped spotsClassic worldwide localities
- Friedensville, Lehigh Co., Pennsylvania, USA
- Linden, Iowa Co., Wisconsin, USA
- Joplin, Jasper Co., Missouri, USA
- Galena, Cherokee Co., Kansas, USA
- Bleiberg, Carinthia, Austria
- Monte Malfidano, near Buggerru, and in the Gutturu Pala mine, north of Iglesias, Sardinia, Italy
Field-hunting tip
Where it forms: Uncommonly formed in the oxidized portions of zinc-bearing deposits, at the expense of sphalerite or smithsonite, and as incrustations in mine workings and caves. If you start seeing smithsonite, hemimorphite, willemite in float, you are in the right ground. Typical habit: bladed, massive, stalactitic. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Nevada, New Mexico, North Carolina. Start trip planning there.
Common questions
How do you identify hydrozincite?+
Where is hydrozincite found?+
Can I find hydrozincite in the United States?+
What rocks look like hydrozincite?+
What minerals are found with hydrozincite?+
What kind of rock does hydrozincite form in?+
What is hydrozincite used for?+
Find hydrozincite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
