Roedderite is a rare member of the osumilite group found primarily in inclusions within volcanic rocks. It typically occurs as small colorless or white tabular crystals that are difficult to distinguish from other silicates without chemical analysis.

Hardness

5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent to translucent

mineralrareOsumilite Group family

Roedderite

Hardness: 5-6
Luster: Vitreous
Streak: White
Transparency: Transparent to translucent

Is this roedderite?

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 roedderite with a known reference. Roedderite sits at Mohs 5-6, 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, blue green, yellow, reddish brown.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: tabular crystals, anhedral grains.

Often confused with

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

mineral

Osumilite

Mohs 5-5.5

How to tell apart: Streak differs, so Roedderite leaves white, Osumilite leaves blue-gray.

Often found alongside roedderite

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

All properties

Chemical formula: (Na,K)₂Mg₅Si₁₂O₃₀
Mohs hardness: 5-6
Density: 2.6 g/cm³
Colors: Colorless Blue green Yellow Reddish brown
Streak: White
Luster: Vitreous
Transparency: Transparent to translucent
Crystal system: Hexagonal
Crystal habit: Tabular crystals, anhedral grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In vesicles in contact metamorphosed basement gneiss xenoliths in leucite tephrite (Bellerberg volcano, Germany); an accessory mineral in an enstatite chondrite (Indarch meteorite)

Where rockhounds find roedderite

Classic worldwide localities

Indarch, Witchita County, and Canyon Diablo meteorites
Bellerberg volcano, two km north of Mayen, Eifel district, Germany

Field-hunting tip

Where it forms: In vesicles in contact metamorphosed basement gneiss xenoliths in leucite tephrite (Bellerberg volcano, Germany); an accessory mineral in an enstatite chondrite (Indarch meteorite). If you start seeing hematite, tridymite, sanidine in float, you are in the right ground. Typical habit: tabular crystals, anhedral grains. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify roedderite?+

Mohs hardness is 5-6. Luster: vitreous. The streak is white. Common colors include colorless, blue green, yellow, reddish brown.

Where is roedderite found?+

Notable localities include Indarch, Witchita County, and Canyon Diablo meteorites; Bellerberg volcano, two km north of Mayen, Eifel district, Germany.

What rocks look like roedderite?+

Roedderite is most often confused with Osumilite, Merrihueite, Sugilite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with roedderite?+

Roedderite commonly co-occurs with Hematite, Tridymite, Sanidine, Spinel, Pyroxene, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does roedderite form in?+

Where it forms: In vesicles in contact metamorphosed basement gneiss xenoliths in leucite tephrite (Bellerberg volcano, Germany); an accessory mineral in an enstatite chondrite (Indarch meteorite). Working float back to the host body is the standard way to chase a fresh occurrence.

What is roedderite used for?+

Roedderite is used in collector.

Find roedderite on the map

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