Tadzhikite
(Ca,Ce)_3-4(Y,Ce)₂(Ti,Al,Fe³⁺)B₄Si₄O₂₂(O,OH)₂

     Tadzhikite was first found in 1974 at MSH and designated UK #39. It is a rare mineral at Mont Saint-Hilaire. Formerly tadzhikite-(Ce) from MSH, we should just use tadzhikite until the issue with nomenclature is resolved (reference new MSH Official Species List published by Malcolm Back, Bob Gault and Bob Ramik). The species is being analysed again, and both the -(Y) and -(Ce) are now valid IMA species.

PHYSICAL CHARACTERISTICS:

Color is usually pale brown to yellowish-brown.
Luster is dull to pearly.
Diaphaneity is translucent to opaque.
Crystal System is monoclinic; P2/a.
Crystal Habits include small rosettes, compact spherical aggregates to
   3mm with lamellar structure, botyroidal masses and irregular thin flakes.
Cleavage {100} is good.
Fracture is (??).
Hardness is 6.
Specific Gravity is approximately 3.8 g/cm³.
Streak is white.
Associated Minerals include aegirine, albite, amphibole group, ancylite,
   calcite, carbocernaite, donnayite, gotzenite, hydrogrossular, lorenzenite,
   microcline, natrolite, parisite, pectolite, penkvilksite, synchysite and
   titanite.
Distinguishing Features: Crystal habit and color.
Origin: Named in 1970 for its discovery locality, in Turkestana, in
   Tadzhikistan

CLASSIFICATION:

REFERENCES:
MinRec 21:342 (1990), Dana 8:1128 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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