Ashcroftine-(Y)
K₅Na₅(Y,Ca)₁₂Si₂₈O₇₀(OH)₂(CO₃)₈ · 3H₂O

     Ashcroftine-(Y) had been originally described as kalithompsonite in 1924. MSH is only the second locality for this species which has the distinction of having the largest unit-cell dimensions of all known species.

PHYSICAL CHARACTERISTICS:

Color is usually very pale violet, pale pink or white.
Luster is vitreous to silky.
Diaphaneity is transparent to translucent.
Crystal System is tetragonal; I4/mmm.
Crystal Habits include very fine divergent sprays and tufts of
   randomly oriented capillary to fibrous crystals to 20mm.
Cleavage {100} is perfect and {001} is good.
Fracture is uneven.
Hardness is 5 - 5.5.
Specific Gravity is approximately 2.25 g/cm³.
Streak is white.
Associated Minerals include aegirine, albite, amphibole group,
   analcime, ancylite, bastnäsite, biotite, brookite, catapleiite,
   cordylite, donnayite, elpidite, ewaldite, fluorapatite, fluorite,
   leucophanite, leucosphenite, lorenzenite, microcline,
   molybdenite, monteregianite, narsarsukite, nepheline, raite
   and zircon.
Distinguishing Features: Crystal habit and color.
Origin: Named in 1933 for Frederik Noel Ashcroft (1878-1949),
    a proeminent mineral collector of London.

CLASSIFICATION:

REFERENCES:
MinRec 21:295-296 (1990), Dana 8:1401 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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