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Silicate

Caysichite-(Y)

(Ca,Yb,Er)₄Y₄(Si₈O₂₀)(CO₃)₆(OH)·7H₂O
Hardness4.5
Crystal systemOrthorhombic
ClassSilicate
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Caysichite-(Y) specimen

Caysichite-(Y), is not an aesthetic mineral but it has the particularity of being the only mineral from more than 5500 minerals known with the very rare chemical element erbium in its chemical composition. From: Evans Lou Mine, Lac Saint Pierre, Québec, Canada. — Photo: David Hospital · CC BY-SA 4.0

Caysichite-(Y)

Caysichite-(Y) is an IMA-recognized mineral species in the silicate class, with the chemical formula (Ca,Yb,Er)₄Y₄(Si₈O₂₀)(CO₃)₆(OH)·7H₂O.

It crystallizes in the orthorhombic crystal system (space group Ccm2_1).

Key properties: Mohs hardness 4.5; specific gravity 3.03; White streak; Vitreous luster; optically biaxial.

IMA symbol Cay-Y, IMA status: approved, named in 1973.

Found in perthite surrounding the quartz core of a granite pegmatite, coating fractures and filling cavities in quartz, perthite, or hellandite; apparently of secondary origin.

It is found associated with Quartz, hellandite, fergusonite, kainosite, tengerite, lokkaite, yttrian thorogummite, yttrian spessartine, xenotime, wakefieldite-(Y), synchysite-(Y).

The name refers to the chemical composition: Ca, Y, Si, C, H.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet. Browse more C minerals or help write this entry.