Krásnoite is a rare calcium aluminum hydroxide. It was approved as a distinct mineral species in 2011, from material found in Czech Republic / USA.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareWardite Group family

Krásnoite

Krásnoite is a rare calcium aluminum hydroxide. It was approved as a distinct mineral species in 2011, from material found in Czech Republic / USA.

Hardness: 4
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this krásnoite?

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 krásnoite with a known reference. Krásnoite sits at Mohs 4, 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: white, colorless.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: tabular crystals.

Often confused with

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

mineral

Wardite

Mohs 5

How to tell apart: Wardite is the harder of the two (Mohs 5 vs. 4).

How to tell apart: Gorceixite is the harder of the two (Mohs 6 vs. 4).

Compare →

Often found alongside krásnoite

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

All properties

Chemical formula: Ca₃Al₇.₇Si₃P₄O₂₃.₅(OH)₁₂.₁F₂·8H₂O
Mohs hardness: 4
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Tetragonal
Crystal habit: Tabular crystals
Cleavage: Good
Rarity: Rare
Uses: Collector
Host rock: tin-bearing greisen deposits

Where rockhounds find krásnoite

Classic worldwide localities

Krásno, Czech Republic
Horni Slavkov, Czech Republic

Field-hunting tip

Where it forms: tin-bearing greisen deposits. If you start seeing fluorapatite, cassiterite, turquoise in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify krásnoite?+

Mohs hardness is 4. Luster: vitreous. The streak is white. Common colors include white, colorless.

Where is krásnoite found?+

Notable localities include Krásno, Czech Republic; Horni Slavkov, Czech Republic.

What rocks look like krásnoite?+

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

What minerals are found with krásnoite?+

Krásnoite commonly co-occurs with Fluorapatite, Cassiterite, Turquoise. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does krásnoite form in?+

Where it forms: tin-bearing greisen deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is krásnoite used for?+

Krásnoite is used in collector.

Find krásnoite on the map

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