Home > Mineral Descriptions > Hydroxyapophyllite



Hydroxyapophyllite
KCa4Si8O20(OH,F) · 8H2O

     Hydroxyapophyllite, a member of the apophyllite series, is a moderately rare species at MSH. It is identical in physical appearance and in association to the more common fluorapophyllite.

PHYSICAL CHARACTERISTICS:

Color is usually colorless, white, pale yellow, greenish-yellow,
   pale green, pink, light tan, bluish-gray.
Luster is vitreous to pearly.
Diaphaneity is transparent to translucent.
Crystal System is tetragonal; P4/mnc.
Crystal Habits include well-formed tabular to equant crystals
   to 4cm, bipyramidal crystals, platy masses to 3cm and spherical
    to mammillary aggregates to 2mm of tabular crystals.
Cleavage {001} is perfect and {110} is imperfect.
Fracture is uneven.
Hardness is 4.5 - 5.
Specific Gravity is approximately 2.36 g/cm3.
Streak is white.
Associated Minerals include aegirine, albite, amphibole group,
   ancylite, biotite, calcite, catapleiite, fluorite, galena, leucosphenite,
   molybdenite, monteregianite, narsarsukite, natrolite, pectolite,
   phlogopite, polylithionite, pyrrhotite, quartz, stillwelite, titanite,
   vesuvianite and zircon.
Distinguishing Features: Crystal habit and luster.
Origin: Named in 1986 to reflect its hydroxyl content, higher than
   in fluorapophyllite, with which it forms a series (known since 1800,
   end-members named in 1986).

CLASSIFICATION:

Dana System
# 72.3.1.2

Strunz Classification
# VIII/H.01-30

REFERENCES:
MinRec 21:315 (1990), Dana 8:1525-1527 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
--

AP
--

MX
¤¤

SS
--

MC
--

HF
--

BR
--

SX
--

FR
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