Paravauxite
{{Short description|Phosphate mineral}}
{{Infobox mineral|boxbgcolor=#c5f0af|image=Paravauxite-179881.jpg|formula=Fe2+Al2(PO4)2(OH)2 · 8H2O| IMAsymbol = Pvx{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3 |pages=291–320|doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 |doi-access=free}}|strunz=8.DC.30|system=Triclinic|dana=42.11.14.2|class=Pinacoidal
H-M Symbol: {{overline|1}}|symmetry=P{{overline|1}}|unit cell=334.43|molweight=477.89|color=Light brown, pale greenish white, gray-white, colorless|cleavage=Perfect on {010}|fracture=Conchoidal|tenacity=Brittle|mohs=3|luster=Sub-Vitreous, resinous, waxy, pearly|opticalprop=Biaxial (+)|refractive=nα = 1.552 - 1.554
nβ = 1.558 - 1.559
nγ = 1.572 - 1.573|birefringence=0.020|pleochroism=None|2V=Measured: 72°
Calculated: 74°|dispersion=Weak to distinct|extinction=X (61°,56°)
Y (180°, 55°)
Z (-61°, 54°)|streak=White|gravity=2.36|density=Measured: 2.36
Calculated: 2.37|diaphaneity=Transparent, translucent}}Paravauxite is a rare phosphate mineral that was named in 1922. Its name is a portmanteau word made by blending the Greek word for near (παρα, meaning para) and vauxite due to the chemical relationship to vauxite. It was approved by the IMA, and was first described in 1959. It is now grandfathered, meaning it is probably to remain a species.{{Cite web|title=Paravauxite|url=https://www.mindat.org/min-3118.html|access-date=2021-10-11|website=www.mindat.org}}
Properties
It is a member of the laueite supergroup, and the laueite group within said supergroup. It is metavauxite's triclinic dimorph. It can form in complex granitic pegmatites, and in hydrothermal tin veins. It forms thick tabular crystals on {010}, and short prismatic ones on [001], but numerous forms might be exhibited. Forms aggregates that are subparallel to radial. The mineral is colorless in transmitted light. It mainly consists of oxygen (60.26%), but contains phosphorus (12.96%), iron (11.69%), aluminum (11.29%) and hydrogen (3.80%) as well. It doesn't show any radioactive properties whatsoever.{{Cite web|title=Paravauxite Mineral Data|url=http://webmineral.com/data/Paravauxite.shtml#.YWP4FBBBzrt|access-date=2021-10-11|website=webmineral.com}} It occurs in tin mines. Paravauxite has a vitreous luster, with one exception on b(100), where it is pearly. It grows in small crystals, which's size can reach up to 5×2×1.5 mm. Crystals are somewhat flattened parallel to b(100). Even with atmospheric humidity, paravauxite's hydrogen dioxide content varies considerably. The mineral's formula is complex, that's why it's really unlikely that it gets simplified by further analyses. There's only one occurrence where vauxite and paravauxite are seen together in one specimen. It's a small, cavernous, mass of druzy-green wavellite. It has blue vauxite in small radial aggregates, and a singular colorless paravauxite. One of blue vauxite's radial aggregates has this crystal implanted on top.{{Cite journal|last=Gordon|first=Samuel G.|date=1923|title=Vauxite and Paravauxite, Two New Minerals from Llallagua, Bolivia|url=https://www.jstor.org/stable/4063881|journal=Proceedings of the Academy of Natural Sciences of Philadelphia|volume=75|pages=261–270|jstor=4063881|issn=0097-3157}}
Formation and mining
Other than vauxite and metavauxite, it is also associated with wavellite, but rarely occurs on the latter. It is the type locality of Llallagua, Bolivia. It can also be found in Germany, Mexico, the United States, Portugal, Sweden, with a couple of other countries.{{Cite web|last=Minerals|first=Dakota Matrix|title=Paravauxite mineral information and data|url=https://www.dakotamatrix.com/mineralpedia/7689/paravauxite|access-date=2021-10-11|website=www.dakotamatrix.com|language=en}}