Paralaurionite

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Paralaurionite
Paralaurionite.jpg
Platey clear paralaurionite crystals from slag in the Thorikos area, Lavrion, Attica, Greece
General
CategoryHalide mineral
Formula
(repeating unit)
PbCl(OH)
Strunz classification3.DC.05
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/m
Unit cella = 10.865(4) Å,
b = 4.006(2) Å,
c = 7.233(3) Å;
β = 117.24(4)°; Z = 4
Identification
ColorColorless, white, pale greenish, yellowish, yellow-orange, rarely violet
Crystal habitElongated tabular crystals
TwinningContact twinning on {100}
CleavagePerfect on {001}
TenacityFlexible, non-elastic
Mohs scale hardness3
LusterSubadamantine
DiaphaneityTransparent to translucent
Specific gravity6.05–6.15
Optical propertiesBiaxial (-)
Refractive indexnα = 2.050 nβ = 2.150 nγ = 2.200
Birefringenceδ = 0.150
PleochroismVisible
References[1][2][3][4]

Paralaurionite is a colorless mineral consisting of a basic lead chloride PbCl(OH) that is dimorphous with laurionite. It is a member of the matlockite group.[5] The name is derived from para-, the Greek for "near", and laurionite, because of its polymorphic relationship to it.[3] Bright, yellow tips of thorikosite can form on paralaurionite crystals and paralaurionite may also be intergrown with mendipite.[6][7]

Occurrence[edit]

It was first described in 1899 for an occurrence in slag in Laurium, Attica, Greece.[2] In 1952 an occurrences of it was reported from the Mammoth Mine, Arizona.[8]

It occurs in lead bearing slag which has been exposed to seawater. It also occurs in polymetallic ore deposits. It occurs associated with laurionite, penfieldite, fiedlerite, phosgenite in slag deposits; and with leadhillite, matlockite, cerussite, hydrocerussite, diaboleite and wherryite in the Mammoth mine location.[2]

References[edit]

  1. ^ Mineralienatlas
  2. ^ a b c Handbook of Mineralogy
  3. ^ a b Paralaurionite on Mindat.org
  4. ^ Paralaurionite on Webmineral
  5. ^ Mineralogical magazine. Mineralogical Society, HighWire Press. 1 January 2006. pp. 643–8. Retrieved 26 January 2012.
  6. ^ The Mineralogical record. 1986. pp. 185–88. Retrieved 26 January 2012.
  7. ^ Williams, Peter A. (August 1990). Oxide zone geochemistry. E. Horwood. pp. 262–4. ISBN 978-0-13-647553-8. Retrieved 26 January 2012.
  8. ^ Mineralogical Society (Great Britain) (1952). The Mineralogical magazine and journal of the Mineralogical Society. Mineralogical Society. pp. 341–2. Retrieved 26 January 2012.
Unusually large crystals of Paralaurionite, Touissit, Oujda-Angad Province, Morocco. Size: 6 x 5.5 x 5 cm.