Katerinopoulosite is an extremely rare ammonium-iron sulfate mineral found primarily in the historic mine dumps of the Lavrion District in Greece. It typically forms as delicate, white, acicular crystal sprays or coatings associated with other secondary sulfate minerals in oxidized hydrothermal deposits.

Hardness

2.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent to translucent

mineralrareKieserite Group family

Katerinopoulosite

Hardness: 2.5
Luster: Vitreous
Streak: White
Transparency: Transparent to translucent

Is this katerinopoulosite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch katerinopoulosite with a known reference. Katerinopoulosite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: colorless, pale blue, or pale green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: acicular to fibrous aggregates.

Often confused with

Katerinopoulosite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Hexahydrite

Mohs 2-2.5

How to tell apart: Luster reads vitreous on Katerinopoulosite and pearly to vitreous on Hexahydrite.

Often found alongside katerinopoulosite

Minerals reported to co-occur with katerinopoulosite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: (NH₄)₂Zn(SO₄)₂·6H₂O
Mohs hardness: 2.5
Density: 1.97 g/cm³
Colors: Colorless Pale blueOr pale green
Streak: White
Luster: Vitreous
Transparency: Transparent to translucent
Crystal system: Monoclinic
Crystal habit: Acicular to fibrous aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral formed in the oxidation zone of a sphalerite-rich deposit situated in the contact zone between calcite marble and mica schist

Where rockhounds find katerinopoulosite

Classic worldwide localities

Esperanza mine, Lavrion District, Attikí Prefecture, Greece

Field-hunting tip

Where it forms: A secondary mineral formed in the oxidation zone of a sphalerite-rich deposit situated in the contact zone between calcite marble and mica schist. If you start seeing chalcanthite, nickelboussingaultite, ammoniojarosite in float, you are in the right ground. Typical habit: acicular to fibrous aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify katerinopoulosite?+

Mohs hardness is 2.5. Luster: vitreous. The streak is white. Common colors include colorless, pale blue, or pale green.

Where is katerinopoulosite found?+

Notable localities include Esperanza mine, Lavrion District, Attikí Prefecture, Greece.

What rocks look like katerinopoulosite?+

Katerinopoulosite is most often confused with Hexahydrite, Melanterite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with katerinopoulosite?+

Katerinopoulosite commonly co-occurs with Chalcanthite, Nickelboussingaultite, Ammoniojarosite, Aurichalcite, Goethite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does katerinopoulosite form in?+

Where it forms: A secondary mineral formed in the oxidation zone of a sphalerite-rich deposit situated in the contact zone between calcite marble and mica schist. Working float back to the host body is the standard way to chase a fresh occurrence.

What is katerinopoulosite used for?+

Katerinopoulosite is used in collector.

Find katerinopoulosite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.