Paralaurionite

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Paralaurionite
Paralaurionite.jpg
Platey clear paralaurionite crystals from slag in the Thorikos area, Lavrion, Attica, Greece
General
Category Halide mineral
Formula
(repeating unit)
PbCl(OH)
Strunz classification 3.DC.05
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group C2/m
Unit cell a = 10.865(4) Å,
b = 4.006(2) Å,
c = 7.233(3) Å;
β = 117.24(4)°; Z = 4
Identification
Color Colorless, white, pale greenish, yellowish, yellow-orange, rarely violet
Crystal habit Elongated tabular crystals
Twinning Contact twinning on {100}
Cleavage Perfect on {001}
Tenacity Flexible, non-elastic
Mohs scale hardness 3
Luster Subadamantine
Diaphaneity Transparent to translucent
Specific gravity 6.05–6.15
Optical properties Biaxial (-)
Refractive index nα = 2.050 nβ = 2.150 nγ = 2.200
Birefringence δ = 0.150
Pleochroism Visible
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.