Oxynatromicrolite is a rare member of the pyrochlore supergroup occurring primarily in tantalum-rich granitic pegmatites. It is typically found as small, octahedral crystals or massive grains and is highly sought after by collectors specializing in complex oxide species.

Hardness

5-5.5

Mohs

Luster

Greasy to Waxy

Streak

Yellowish Brown

Transparency

Translucent

mineralrarePyrochlore Supergroup family

Oxynatromicrolite

Hardness: 5-5.5
Luster: Greasy to Waxy
Streak: Yellowish Brown
Transparency: Translucent

No image

Is this oxynatromicrolite?

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 oxynatromicrolite with a known reference. Oxynatromicrolite sits at Mohs 5-5.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Oxynatromicrolite leaves a yellowish brown streak.
3
Read the luster
Hold the specimen under a strong light. Oxynatromicrolite typically shows a greasy to waxy luster.
4
Match the color range
Compare against the expected color range: yellow, brown, colorless.
5
Look at form & habit
Crystal system: cubic. Typical habit: octahedral crystals, massive.

Often found alongside oxynatromicrolite

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

All properties

Chemical formula: (Na,Ca,◻)₂(Ta,Nb)₂O₆(O,OH,F)
Mohs hardness: 5-5.5
Density: 5.5-6.5 g/cm³
Colors: Yellow Brown Colorless
Streak: Yellowish Brown
Luster: Greasy to Waxy
Transparency: Translucent
Crystal system: Cubic
Crystal habit: Octahedral Crystals, Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatites

Where rockhounds find oxynatromicrolite

Classic worldwide localities

Sweden
Russia
Brazil
Canada

Field-hunting tip

Look in granite pegmatites country, the host setting where oxynatromicrolite typically forms. If you start seeing albite, quartz, microcline in float, you are in the right ground. Field specimens usually show a octahedral crystals, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify oxynatromicrolite?+

Mohs hardness is 5-5.5. It typically shows a greasy to waxy luster. The streak is yellowish brown. Common colors include yellow, brown, colorless.

Where is oxynatromicrolite found?+

Notable localities include Sweden; Russia; Brazil; Canada.

Is oxynatromicrolite safe to handle?+

This mineral is radioactive. Contains minor amounts of radioactive elements like thorium and uranium; wash hands after handling and store away from prolonged contact. Handle with care, avoid grinding or breathing dust, and store separately.

What minerals are found with oxynatromicrolite?+

Oxynatromicrolite commonly co-occurs with Albite, Quartz, Microcline, Lepidolite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does oxynatromicrolite form in?+

Oxynatromicrolite typically forms in granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is oxynatromicrolite used for?+

Oxynatromicrolite is used in collector.

Find oxynatromicrolite on the map

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