Yoderite is an exceptionally rare metamorphic silicate mineral primarily known from the Mautia Hill locality in Tanzania. It typically appears as deep violet to purple tabular crystals embedded within kyanite-bearing schists and is highly sought after by advanced mineral collectors.

Hardness

6.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrare

Yoderite

Hardness: 6.5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this yoderite?

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 yoderite with a known reference. Yoderite sits at Mohs 6.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Yoderite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Yoderite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: deep violet, lavender, purple.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals.

Often confused with

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

How to tell apart: Luster reads vitreous on Yoderite and vitreous to resinous on Staurolite.

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Often found alongside yoderite

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

All properties

Chemical formula: (Mg,Al)₆Si₄O₁₂(OH)₂
Mohs hardness: 6.5
Density: 3.4 g/cm³
Colors: Deep Violet Lavender Purple
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals
Cleavage: Distinct in One Direction
Rarity: Rare
Uses: Collector
Host rock: Kyanite-talc-chlorite Schists
Typical price: $50-300 per specimen

Where rockhounds find yoderite

Classic worldwide localities

Mautia Hill, Tanzania
Tanzania

Field-hunting tip

Look in kyanite-talc-chlorite schists country — that is the host setting where yoderite typically forms. If you start seeing kyanite, talc, chlorite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify yoderite?+

Mohs hardness is 6.5. It typically shows a vitreous luster. The streak is white. Common colors include deep violet, lavender, purple.

Where is yoderite found?+

Notable localities include Mautia Hill, Tanzania; Tanzania.

How much is yoderite 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.

What rocks look like yoderite?+

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

What minerals are found with yoderite?+

Yoderite commonly co-occurs with Kyanite, Talc, Chlorite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does yoderite form in?+

Yoderite typically forms in kyanite-talc-chlorite schists. Working float back to the host body is the standard way to chase a fresh occurrence.

What is yoderite used for?+

Yoderite is used in collector.

Find yoderite on the map

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