Hundholmenite-(Y) is a rare yttrium-rich member of the apatite group characterized by its yellowish-brown prismatic crystals. It is primarily found in complex granite pegmatites and is sought after by advanced collectors for its rarity and distinct chemical composition.

Hardness

~5-6

Mohs

Luster

Vitreous to adamantine

Streak

White

Transparency

Translucent

mineralrareApatite Group family

Hundholmenite-(Y)

Hardness: ~5-6
Luster: Vitreous to adamantine
Streak: White
Transparency: Translucent

No image

Is this hundholmenite-(y)?

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 hundholmenite-(y) with a known reference. Hundholmenite-(Y) 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 to adamantine.
4
Match the color range
Compare against the expected color range: pale brown.
5
Look at form & habit
Crystal system: trigonal. Typical habit: inclusions, subhedral crystals.

Often confused with

Hundholmenite-(Y) vs. its common look-alikes, and how to tell them apart in the field.

All properties

Chemical formula: (Y,REE,Ca,Na)₁₅(Al,Fe)CaxAs₁-x(Si,As)Si₆B₃(O,F)₄₈
Mohs hardness: ~5-6
Density: 5.206 g/cm³
Colors: Pale brown
Streak: White
Luster: Vitreous to adamantine
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Inclusions, subhedral crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: A late-stage, primary mineral in granite pegmatite

Where rockhounds find hundholmenite-(y)

Classic worldwide localities

Hundholmen (type locality), 7 km northwest of Kjøpsvik, and at Stetind, Tysfjord, and at Lagmannsvik, Hamarøy, Nordland County, Norway

Field-hunting tip

Where it forms: A late-stage, primary mineral in granite pegmatite. If you start seeing ree-bearing fluorite, allanite- in float, you are in the right ground. Typical habit: inclusions, subhedral crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify hundholmenite-(y)?+

Mohs hardness is ~5-6. Luster: vitreous to adamantine. The streak is white. Common colors include pale brown.

Where is hundholmenite-(y) found?+

Notable localities include Hundholmen (type locality), 7 km northwest of Kjøpsvik, and at Stetind, Tysfjord, and at Lagmannsvik, Hamarøy, Nordland County, Norway.

Is hundholmenite-(y) safe to handle?+

Hundholmenite-(Y) contains arsenic and calls for real care. Contains rare earth elements and thorium, handle with care and wash hands after contact. Store away from living spaces to minimize radon exposure.

What rocks look like hundholmenite-(y)?+

Hundholmenite-(Y) is most often confused with Apatite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with hundholmenite-(y)?+

Hundholmenite-(Y) commonly co-occurs with REE-bearing fluorite, Allanite-. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does hundholmenite-(y) form in?+

Where it forms: A late-stage, primary mineral in granite pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is hundholmenite-(y) used for?+

Hundholmenite-(Y) is used in collector.

Find hundholmenite-(y) on the map

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