| Paralaurionite | |
| Category: | Halide mineral |
| Formula: | PbCl(OH) |
| Imasymbol: | Plri[1] |
| Strunz: | 3.DC.05 |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | 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 |
| Color: | Colorless, white, pale greenish, yellowish, yellow-orange, rarely violet |
| Habit: | Elongated tabular crystals |
| Twinning: | Contact twinning on |
| Cleavage: | Perfect on |
| Tenacity: | Flexible, non-elastic |
| Mohs: | 3 |
| Luster: | Subadamantine |
| Diaphaneity: | Transparent to translucent |
| Gravity: | 6.05–6.15 |
| Opticalprop: | Biaxial (−) |
| Refractive: | nα = 2.050 nβ = 2.150 nγ = 2.200 |
| Birefringence: | δ = 0.150 |
| Pleochroism: | Visible |
| References: | [2] [3] [4] [5] |
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.[6] The name is derived from para-, the Greek for "near", and laurionite, because of its polymorphic relationship to it.[4] Bright, yellow tips of thorikosite can form on paralaurionite crystals and paralaurionite may also be intergrown with mendipite.[7] [8]
It was first described in 1899 for an occurrence in slag in Laurium, Attica, Greece.[3] In 1952 an occurrences of it was reported from the Mammoth Mine, Arizona.[9]
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.[3]