Alumoåkermanite is a rare member of the melilite group typically found in contact metamorphic skarns. It usually occurs as small, tabular crystals associated with other calcium silicates in environments where limestone has been altered by igneous intrusions.

Hardness

4-5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareMelilite Group family

Alumoåkermanite

Hardness: 4-5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this alumoåkermanite?

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 alumoåkermanite with a known reference. Alumoåkermanite sits at Mohs 4-5, 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, white, gray, yellowish.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: tabular.

Often confused with

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

Often found alongside alumoåkermanite

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

All properties

Chemical formula: (Ca,Na)₂(Al,Mg,Fe²⁺)(Si₂O₇)
Mohs hardness: 4-5
Density: 2.95 g/cm³
Colors: Colorless White Gray Yellowish
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Tetragonal
Crystal habit: Tabular
Cleavage: Distinct on {001}
Rarity: Rare
Uses: Collector
Host rock: Found in evolved olivine free melilite-nephelinitic ashes and lapilli-tuffs as a silicate phase in non-carbonatite lavas

Where rockhounds find alumoåkermanite

Classic worldwide localities

Oldoinyo Lengai volcano, Tanzania (type locality)

Field-hunting tip

Where it forms: Found in evolved olivine free melilite-nephelinitic ashes and lapilli-tuffs as a silicate phase in non-carbonatite lavas. If you start seeing calcite, wollastonite, diopside in float, you are in the right ground. Typical habit: tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify alumoåkermanite?+

Mohs hardness is 4-5. Luster: vitreous. The streak is white. Common colors include colorless, white, gray, yellowish.

Where is alumoåkermanite found?+

Notable localities include Oldoinyo Lengai volcano, Tanzania (type locality).

What rocks look like alumoåkermanite?+

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

What minerals are found with alumoåkermanite?+

Alumoåkermanite commonly co-occurs with Calcite, Wollastonite, Diopside, Garnet. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does alumoåkermanite form in?+

Where it forms: Found in evolved olivine free melilite-nephelinitic ashes and lapilli-tuffs as a silicate phase in non-carbonatite lavas. Working float back to the host body is the standard way to chase a fresh occurrence.

What is alumoåkermanite used for?+

Alumoåkermanite is used in collector.

Find alumoåkermanite on the map

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