Hellandite-(Y) is a rare yttrium-calcium sorosilicate found primarily in granitic pegmatites. It typically occurs as brown, vitreous, prismatic crystals that are often altered, making high-quality intact specimens highly sought after by mineral collectors.
Is this hellandite-(y)?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch hellandite-(y) with a known reference. Hellandite-(Y) sits at Mohs 4.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to dull.
- 4Match the color rangeCompare against the expected color range: green yellow, grayish black, reddish brown, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic.
Often confused with
Hellandite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Hellandite-(Y) leaves white, Allanite leaves gray; luster reads vitreous to dull on Hellandite-(Y) and submetallic on Allanite.
How to tell apart: Streak differs, so Hellandite-(Y) leaves white, Gadolinite-(Y) leaves greenish gray.
How to tell apart: Zircon is the harder of the two (Mohs 7.5 vs. 4.5-6.5).
Often found alongside hellandite-(y)
Minerals reported to co-occur with hellandite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,REE)₄Y₂Al□₂(B₄Si₄O₂₂)(OH)₂
- Mohs hardness
- 4.5-6.5
- Density
- 2.95-3.63 g/cm³
- Streak
- White
- Luster
- Vitreous to dull
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic
- Cleavage
- Poor on {100}, {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In granite pegmatite (Norway; Wakefield Lake, Canada)
Where rockhounds find hellandite-(y)
Classic worldwide localities
- Crestmore, Riverside Co., California, USA
- Lindvikskollen pegmatite, near Kragerö and the Heftetjern pegmatite, Tørdal, Telemark, Norway
- Predazzo, Trentino-Alto Adige, Italy
- Lago Vico, Viterbo, and near Vetralla, Lazio, Italy
- Evans-Lou quarry, near Wakefield Lake, Quebec, Canada
Field-hunting tip
Where it forms: In granite pegmatite (Norway; Wakefield Lake, Canada). If you start seeing tourmaline, thorite, allanite in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hellandite-(y)?+
Where is hellandite-(y) found?+
Is hellandite-(y) safe to handle?+
What rocks look like hellandite-(y)?+
What minerals are found with hellandite-(y)?+
What kind of rock does hellandite-(y) form in?+
What is hellandite-(y) used for?+
Find hellandite-(y) on the map
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