APOPHYLLITE: Hydrated Potassium Calcium Sodium Silicate Fluoride Hydroxide

APOPHYLLITE

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APPLICATIONS:

Mineral specimens.

ASSOCIATED MINERALS:

Prehnite, quartz, heulandite, stilbite, natrolite, analcime, datolite, babingtonite, cavansite, calcite, idocrase, wollastonite, kinoite, gyrolite and many other zeolites.

CHEMICAL STRUCTURE:

(K,Na)Ca4Si8O20(F,OH) - 8H2O, Hydrated Potassium Calcium Sodium Silicate Fluoride Hydroxide.

CLASS:

Silicates.

CLEAVAGE:

Perfect in one direction (basal).

COLOR:

Clear, white, green, yellow, pink, violet or rarely brown.

CRYSTRAL HABITS:

Four sided prisms (with a square cross-section) truncated with either a steep four sided pyramid or a pinacoid termination or both. If the pyramids are missing, the crystals can look cubic. Rarely are the prisms missing, but if they are, crystals could appear octahedral because of the four sided pyramids. The faces of the pyramids do not lineup with the prism faces but with their edges, therefore the pyramid faces have four edges and appear diamond shaped instead of triangular like the pyramid faces of quartz. Rare tabular hydroxyapophyllite crystals are also known.

CRYSTAL SYSTEM:

Tetragonal, 4/m 2/m 2/m. Natroapophyllite is orthorhombic, 2/m 2/m 2/m.

FIELD INDICATORS:

crystal habit, striations, associations, environment of formation, cleavage and luster on cleavage surfaces.

FRACTURE:

Uneven.

GENERAL INFORMATION:

Prism faces are striated lengthwise, some specimens are fluorescent and crystals will flake when heated.

GEOGRAPHY:

Deccan Traps, India (especially around Poona), also found in Christmas Mine, Arizona; Fairfax, Virginia; Upper Peninsula, Michigan; Oregon; Pennsylvania; Paterson, New Jersey and North Carolina, USA; Rio Grande do Sul, Brazil; Isle of Skye, Scotland; Collinward, Northern Ireland; Mexico; Nova Scotia and Mont Saint-Hilaire, Canada; Iceland; Kongsberg, Norway; Harz Mountains, Germany and Sampo Mine, Takahashi, Okayama, Honshu, Japan.

GROUP:

Apophyllite.

HARDNESS:

4.5 - 5.

LUSTER:

Vitreous to pearly on cleavage surfaces.

TRANSPARENCY:

Transparent to translucent.

SPECIFIC GRAVITY:

2.3 - 2.4.

STREAK:

White.

SUBCLASS:

Phyllosilicates.


THE OFFICIAL APOPHYLLITES

MINERAL:
FORMULA:
SYMMETRY:
COLOR RANGE:
TYPE LOCALITY:
FLUORESCENCE:
FLUOR-
APOPHYLLITE		 (K, Na)Ca4
Si8O20(F,OH) - 8H2O		 Tetragonal;
4/m 2/m 2/m		 White, colorless, green, yellow or violet Not named Some specimens fluoresce pale green or yellow
HYDROXY-
APOPHYLLITE		 KCa4
Si8O20(OH, F) - 8H2O		 Tetragonal;
4/m 2/m 2/m		 White or colorless Ore Knob Mine, Jefferson, North Carolina Non-fluorescent
NATRO-
APOPHYLLITE		 NaCa4
Si8O20F - 8H2O		 Orthorhombic;
2/m 2/m 2/m (pseudo-
tetragonal)		 brown, brownish yellow, yellow or colorless Sampo Mine, Takahashi, Okayama, Honshu, Japan Non-fluorescent


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