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Centreville, Culpeper Basin, Fairfax Co., Virginia, USA
© 2002 John H. Betts
|System:||Tetragonal||Hardness:||4 - 5|
|Name:||Apophyllite was named in 1806 by Rene Just Haüy from the Greek for "away from" (ἀπό, apo) and "leaf" (φύλλον, phyllos), in allusion to the way it exfoliates upon heating. Chemical variants were recognized by Pete J. Dunn, Roland C. Rouse, and Julie A. Norberg in 1978.|
Mineral name changed from apophyllite-(KOH) to hydroxyapophyllite-(K) (Hatert et al. 2013)
Classification of Hydroxyapophyllite-(K)
|Strunz 8th edition ID:||8/H.01-30|
|Nickel-Strunz 10th (pending) edition ID:||9.EA.15|
9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings
|Hey's CIM Ref.:||17.1.6|
17 : Silicates Containing other Anions
1 : Silicates with fluoride (not containing Al)
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Type Occurrence of Hydroxyapophyllite-(K)
|Type Locality:||Ore Knob Mine, Ore Knob, Ashe Co., North Carolina, USA|
|Year of Discovery:||1978|
Physical Properties of Hydroxyapophyllite-(K)
|Hardness (Mohs):||4 - 5|
Crystallography of Hydroxyapophyllite-(K)
|Cell Parameters:||a = 8.97Å, c = 15.83Å|
|Ratio:||a:c = 1 : 1.765|
|Unit Cell Volume:||V 1,273.70 Å³ (Calculated from Unit Cell)|
|X-Ray Powder Diffraction:|
Radiation - Copper Kα
Data courtesy of RRUFF project at University of Arizona, used with permission.
Optical Data of Hydroxyapophyllite-(K)
|RI values:||nω = 1.542 nε = 1.543|
|Maximum Birefringence:||δ = 0.001|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Chemical Properties of Hydroxyapophyllite-(K)
|Simplified for copy/paste:||KCa4(Si8O20)(OH,F)·8H2O|
|Essential elements:||Ca, H, K, O, Si|
|All elements listed in formula:||Ca, F, H, K, O, Si|
Relationship of Hydroxyapophyllite-(K) to other Species
|Series:||Forms a series with Fluorapophyllite-(K) (see here)|
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Hydroxyapophyllite-(K)
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Hydroxyapophyllite-(K)
Dunn, P. J., Rouse, R. C. & Norberg, J. A. (1978): Hydroxyapophyllite, a new mineral and a redefinition of the apophyllite group. American Mineralogist 63, 196-202.
Dunn, P. J. & Wilson, W. E. (1978): Nomenclature revision in the apophyllite group: hydroxyapophyllite, apophyllite, fluorapophyllite. Min. Record 9, 95-98.
Acta Crystallographica: (1987): B43: 517.
HATERT, F., MILLS, S.J., PASERO, M. and WILLIAMS, P.A. (2013) CNMNC guidelines for the use of suffixes and prefixes in mineral nomenclature, and for the preservation of historical names. European Journal of Mineralogy 25, 113-115.
Internet Links for Hydroxyapophyllite-(K)
|Specimens:||The following Hydroxyapophyllite-(K) specimens are currently listed for sale on minfind.com.|
Localities for Hydroxyapophyllite-(K)
The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.