Name/Title
ApophylliteEntry/Object ID
2013.1.19Description
Chemical Composition: SiO2
Crystal System: Triclinic System
Description: Common Name:Apophyllite
Chemistry: (K,Na)Ca4Si8O20(F,OH)·8H2O
Group: Silicates
Location: Maharashtra, India
Description: This specimen is a tight cluster of large crystals that are transparent.
Physical Description:
The name apophyllite refers to a specific group of phyllosilicates, a class of minerals. 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 apophyllite-(KF), apophyllite-(KOH), and apophyllite-(NaF). The name apophyllite is derived from the Greek ?p?F?????? apophylliso, meaning "it flakes off", a reference to this class's tendency to flake apart when heated, due to water loss. These minerals are typically found as secondary minerals in vesicles in basalt or other volcanic rocks. A recent change in the nomenclature system used for this group was approved by the International Mineralogical Association, removing the prefixes from the species names and using suffixes to designate the species.[2]
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.
Fracture: Conchoidal
Hardness: 7 Quartz
Luster: Pearly
Rock Type: Sedimentary
Specific Gravity: 2.68-2.72
Streak: White
Variety: Apophyllite-(KF) (formerly fluorapophyllite), KCa4Si8O20(F,OH)·8H2O - white, colorless, yellow, green, violet [3]
Apophyllite-(KOH) (formerly hydroxyapophyllite), KCa4Si8O20(OH,F)·8H2O - white, colorless [4]
Apophyllite-(NaF) (formerly natroapophyllite), Na4Si8O20F·8H2O - brown, yellow, colorlessCollection
RAGM Mineral CollectionOther Names and Numbers
Other Number
Other Number: 2009.63.21Dimensions
Width
5 inDepth
3 inLength
5-1/4 inLocation
Location
Display Case
FS-3Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
ExhibitMoved By
Ian C.Date
January 29, 2025Notes
Major mineral groups installationLocation
Display Case
FS-4Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
PermanentDate
August 17, 2023
