Henritermierite is a rare calcium-manganese silicate member of the garnet group that crystallizes in the tetragonal system. It is primarily found as distinct, brownish, dodecahedral crystals in manganese-rich environments, most notably at the Tachgagalt mine in Morocco.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareGarnet Group family

Henritermierite

Hardness: 6
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this henritermierite?

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 henritermierite with a known reference. Henritermierite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Henritermierite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Henritermierite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: brown, reddish-brown.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: dodecahedral crystals.

Often confused with

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

Often found alongside henritermierite

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

All properties

Chemical formula: Ca₃Mn³⁺₂(SiO₄)₂(OH)₄
Mohs hardness: 6
Density: 3.55 g/cm³
Colors: Brown Reddish-brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Tetragonal
Crystal habit: Dodecahedral Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Manganese Ore Deposits
Typical price: $50-500 thumbnail

Where rockhounds find henritermierite

Classic worldwide localities

Tachgagalt, Morocco

Field-hunting tip

Look in manganese ore deposits country, the host setting where henritermierite typically forms. If you start seeing hausmannite, quartz, calcite in float, you are in the right ground. Field specimens usually show a dodecahedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify henritermierite?+

Mohs hardness is 6. It typically shows a vitreous luster. The streak is white. Common colors include brown, reddish-brown.

Where is henritermierite found?+

Notable localities include Tachgagalt, Morocco.

How much is henritermierite worth?+

Typical asking prices fall in the range of $50-500 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like henritermierite?+

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

What minerals are found with henritermierite?+

Henritermierite commonly co-occurs with Hausmannite, Quartz, Calcite, Barite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does henritermierite form in?+

Henritermierite typically forms in manganese ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is henritermierite used for?+

Henritermierite is used in collector.

Find henritermierite on the map

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