Dictionary - Definition of APOPHYLLITE

Definition: APOPHYLLITE


Part of Speech	Definition
Noun	1. A mineral relating to the zeolites, usually occurring in square prisms or octahedrons with pearly luster on the cleavage surface. It is a hydrous silicate of calcium and potassium.[Websters].
Source: Webster's Revised Unabridged Dictionary (1913)		Top

Date "Apophyllite" was first used in popular English literature: sometime before 1828. (references)

Etymology:Apophyllite \A*poph"yl*lite\, noun. [Prefix apo- Greek expression leaf; so called from its foliated structure or easy cleavage.]. (references)

Specialty Definition: APOPHYLLITE

Domain	Definition
Mining	A mineral group, 2[KFCa4 (Si8 O20 ).8H2 O] (fluorapophyllite) with F replaced by (OH) (hydroxyapophyllite) and K replaced by Na (natroapophyllite); occurs in square micaceous crystals assecondary minerals in cavities in igneous rocks. Syn:fisheye stone. (references)
Wikipedic	The name apophyllite refers to a specific group of phyllosilicate minerals, a class of minerals that also includes the micas. Originally, the group name referred to a specific mineral, but was redefined in 1978 to stand for a class of minerals of similar chemical makeup that comprise a solid solution series, and includes the members fluorapophyllite, hydroxyapophyllite, natroapophyllite, and the very rare carletonite. The name apophyllite is derived from the Greek apophylliso, meaning "it flakes off," a reference to this class's tendency flake apart when heated, due to water loss. These minerals are typically found as secondary minerals in basalt. (references)
Source: compiled by the editor from various references; see credits.		Top

Extended Definition: APOPHYLLITE

Apophyllite

Apophyllite

General
Category	Mineral
Chemical formula	(K,Na)Ca₄Si₈O₂₀(F,OH) • 8H₂O
Identification
Color	Usually white, colorless; also blue, green, brown, yellow, pink, violet
Crystal habit	prismatic, tabular, massive
Crystal system	Tetragonal; Orthorhombic (natroapophyllite)
Cleavage	[001] Perfect
Fracture	Uneven
Mohs Scale hardness	4.5 - 5
Luster	Vitreous; Pearly
Refractive index	1.536
Pleochroism	Dichroic (colorless)
Streak	White
Specific gravity	2.3 - 2.4
Diaphaneity	Transparent to translucent

The name apophyllite refers to a specific group of phyllosilicates, a class of minerals that also includes the micas. Originally, the group name referred to a specific mineral, but was redefined in 1978 to stand for a class of minerals of similar chemical makeup that comprise a solid solution series, and includes the members fluorapophyllite, hydroxyapophyllite, and natroapophyllite. The name apophyllite is derived from the Greek apophylliso, meaning "it flakes off," a reference to this class's tendency flake apart when heated, due to water loss. These minerals are typically found as secondary minerals in holes in basalt or other igneous rocks. They can also be called "fisheye stone".^[1]

Though relatively unfamiliar to the general public, apophyllites are fairly prevalent around the world, with specimens coming from some of the world's most well-known mineral localities. These localities include: Poona, India; the Harz Mountains of Germany, Mont Saint-Hilaire in Canada, and Kongsberg, Norway, with other locations in Scotland, Ireland, Brazil, Japan, and throughout the United States.

Uses

Apophyllites are popular as collector's minerals. This popularity is due to a combination of factors, including their abundance, color variety, and well-defined crystals. Naturally forming pyramidal structures, they refract light in obvious rainbows, and can form "natural pyramids" when subjected to rock tumbling.

Species of Apophyllite

Fluorapophyllite, (K, Na)Ca₄Si₈O₂₀(F, OH) · 8H₂O - white, colorless, yellow, green, violet
Hydroxyapophyllite, KCa₄Si₈O₂₀(OH, F) · 8H₂O - white, colorless
Natroapophyllite, (K, Na)Ca₄Si₈O₂₀F · 8H₂O - brown, yellow, colorless

References

http://www.maden.hacettepe.edu.tr/dmmrt/dmmrt50.html#d1040

WebMineral Listing
MinDat Listing
Mineral Galleries
Colville AA, Anderson CP, Black PM (1971). "Refinement of the crystal structure of apophyllite: I. X-ray diffraction and physical properties". American Mineralogist 56: 1222-1233.

Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "Apophyllite". Image Credit.
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Topics by Level of Interest: APOPHYLLITE
Topics sorted by level of Interest	Level (1=low, 600=high)	Topics sorted Alphabetically	Level (1=low, 600=high)
Apophyllite	7	Apophyllite	7
Source: the editor, created by/for EVE to gauge likely levels of human interest in linguistically triggered topics (compiled across various sources, such as Wikipedia and specialty expression glosses).