Klebelsbergite is a rare secondary antimony mineral that typically forms as delicate, acicular crystals or radiating sprays in the oxidation zones of antimony deposits. It is best identified by its adamantine luster and association with other secondary antimony minerals like valentinite. Due to its fragility and rarity, it is highly sought after by advanced systematic collectors.

Hardness

2-2.5

Mohs

Luster

Adamantine

Streak

White

Transparency

Transparent

mineralrare

Klebelsbergite

Hardness: 2-2.5
Luster: Adamantine
Streak: White
Transparency: Transparent

Is this klebelsbergite?

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 klebelsbergite with a known reference. Klebelsbergite sits at Mohs 2-2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Klebelsbergite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Klebelsbergite typically shows a adamantine luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-green, colorless.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: acicular crystals, radiating clusters, crusts.

Often confused with

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

How to tell apart: Stibiconite is the harder of the two (Mohs 5-5.5 vs. 2-2.5); luster reads adamantine on Klebelsbergite and dull on Stibiconite.

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Often found alongside klebelsbergite

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

All properties

Chemical formula: Sb₄O₄(OH)₂SO₄
Mohs hardness: 2-2.5
Density: 4.67 g/cm³
Colors: Yellow Yellowish-green Colorless
Streak: White
Luster: Adamantine
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Acicular Crystals, Radiating Clusters, Crusts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Zones of Antimony Deposits
Typical price: $50-300 per specimen

Where rockhounds find klebelsbergite

Classic worldwide localities

Antimony Mine, Hungary
Pereta mine, Italy
Tuscany, Italy

Field-hunting tip

Look in oxidized zones of antimony deposits country — that is the host setting where klebelsbergite typically forms. If you start seeing stibnite, valentinite, senarmontite in float, you are in the right ground. Field specimens usually show a acicular crystals, radiating clusters, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify klebelsbergite?+

Mohs hardness is 2-2.5. It typically shows a adamantine luster. The streak is white. Common colors include yellow, yellowish-green, colorless.

Where is klebelsbergite found?+

Notable localities include Antimony Mine, Hungary; Pereta mine, Italy; Tuscany, Italy.

How much is klebelsbergite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is klebelsbergite safe to handle?+

It contains toxic constituents. Contains antimony which is toxic if ingested or inhaled as dust. Always wash hands after handling and avoid creating dust when cleaning specimens. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like klebelsbergite?+

Klebelsbergite is most often confused with Valentinite, Senarmontite, Stibiconite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with klebelsbergite?+

Klebelsbergite commonly co-occurs with Stibnite, Valentinite, Senarmontite, Gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does klebelsbergite form in?+

Klebelsbergite typically forms in oxidized zones of antimony deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is klebelsbergite used for?+

Klebelsbergite is used in collector.

Find klebelsbergite on the map

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