Ashcroftine-(Y) is a rare potassium-sodium-yttrium silicate mineral known for its striking pink, radiating, or needle-like crystal aggregates. It is primarily found in highly alkaline pegmatites, often appearing as delicate, fibrous sprays associated with other rare earth minerals.

Hardness

Mohs

Luster

Vitreous, may be silky

Streak

White

Transparency

Transparent to translucent

mineralrare

Ashcroftine-(Y)

Hardness: 5
Luster: Vitreous, may be silky
Streak: White
Transparency: Transparent to translucent

Is this ashcroftine-(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 ashcroftine-(y) with a known reference. Ashcroftine-(Y) sits at Mohs 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, may be silky.
4
Match the color range
Compare against the expected color range: pink, light violet, pinkish brown, deep violet.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: fibrous, prismatic.

Often confused with

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

Often found alongside ashcroftine-(y)

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

All properties

Chemical formula: K₅Na₅Y₁₂Si₂₈O₇₀(OH)₂(CO₃)₈·8H₂O
Mohs hardness: 5
Density: 2.61 g/cm³
Colors: Pink Light violet Pinkish brownDeep violet
Streak: White
Luster: Vitreous, may be silky
Transparency: Transparent to translucent
Crystal system: Tetragonal
Crystal habit: Fibrous, prismatic
Cleavage: Perfect on {100}, distinct on {001}
Fluorescence: Bright white/pale yellow under LW UV
Rarity: Rare
Uses: Collector
Host rock: In cavities in augite syenite (Narssârssuk, Greenland); in igneous breccia and pegmatites in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada)

Where rockhounds find ashcroftine-(y)

Classic worldwide localities

Narssârssuk, Greenland
Mont Saint-Hilaire, Quebec, Canada
Cava del 'Osa, near Rome, Lazio, Italy

Field-hunting tip

Where it forms: In cavities in augite syenite (Narssârssuk, Greenland); in igneous breccia and pegmatites in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada). If you start seeing calcite, elpidite, albite in float, you are in the right ground. Typical habit: fibrous, prismatic. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ashcroftine-(y)?+

Mohs hardness is 5. Luster: vitreous, may be silky. The streak is white. Common colors include pink, light violet, pinkish brown, deep violet.

Where is ashcroftine-(y) found?+

Notable localities include Narssârssuk, Greenland; Mont Saint-Hilaire, Quebec, Canada; Cava del 'Osa, near Rome, Lazio, Italy.

What rocks look like ashcroftine-(y)?+

Ashcroftine-(Y) is most often confused with Scolecite, Mesolite, Thomsonite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

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

Ashcroftine-(Y) commonly co-occurs with Calcite, Elpidite, Albite, Quartz, Aegirine, Orthoclase. Spotting any of these in float or country rock is a useful trip signal.

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

Where it forms: In cavities in augite syenite (Narssârssuk, Greenland); in igneous breccia and pegmatites in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada). Working float back to the host body is the standard way to chase a fresh occurrence.

What is ashcroftine-(y) used for?+

Ashcroftine-(Y) is used in collector.

Find ashcroftine-(y) on the map

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