Silesiaite is a rare iron-rich member of the garnet group historically described from the Silesia region. It typically appears as yellowish to brown dodecahedral crystals formed in metamorphic environments and is highly sought after by systematic mineral collectors.

Hardness

6.5-7

Mohs

Luster

Vitreous

Transparency

Translucent

mineralrareGarnet Group family

Silesiaite

Hardness: 6.5-7
Luster: Vitreous
Transparency: Translucent

No image

Is this silesiaite?

4-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 silesiaite with a known reference. Silesiaite sits at Mohs 6.5-7, softer than the next harder reference, harder than the previous one.
2
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
3
Match the color range
Compare against the expected color range: yellow, brown, greenish.
4
Look at form & habit
Crystal system: triclinic.

Often confused with

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

mineral

Andradite

Mohs 6.5-7

How to tell apart: Luster reads vitreous on Silesiaite and adamantine to resinous, dull on Andradite.

Often found alongside silesiaite

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

All properties

Chemical formula: Ca₄Fe₂Sn₂(Si₂O₇)₂(Si₂O₆OH)₂
Mohs hardness: 6.5-7
Density: 3.5-3.6 g/cm³
Colors: Yellow Brown Greenish
Luster: Vitreous
Transparency: Translucent
Crystal system: Triclinic
Rarity: Rare
Uses: Collector
Host rock: In granitic pegmatite (Poland); in calcic Cu-Au skarn (Spain)

Where rockhounds find silesiaite

Classic worldwide localities

Szklarska Poręba Huta quarry, Lower Silesia, Poland (type locality)
El Valle-Boinás, Asturias, northern Spain

Field-hunting tip

Where it forms: In granitic pegmatite (Poland); in calcic Cu-Au skarn (Spain). If you start seeing andradite, clinopyroxene, actinolite in float, you are in the right ground.

Common questions

How do you identify silesiaite?+

Mohs hardness is 6.5-7. Luster: vitreous. Common colors include yellow, brown, greenish.

Where is silesiaite found?+

Notable localities include Szklarska Poręba Huta quarry, Lower Silesia, Poland (type locality); El Valle-Boinás, Asturias, northern Spain.

What rocks look like silesiaite?+

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

What minerals are found with silesiaite?+

Silesiaite commonly co-occurs with Andradite, Clinopyroxene, Actinolite, Apophyllite-, Babingtonite, Hydroandradite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does silesiaite form in?+

Where it forms: In granitic pegmatite (Poland); in calcic Cu-Au skarn (Spain). Working float back to the host body is the standard way to chase a fresh occurrence.

What is silesiaite used for?+

Silesiaite is used in collector.

Find silesiaite on the map

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