Marthozite

{{Infobox mineral

| name = Marthozite

| category = Oxide mineral (uranyl selenite)

| boxwidth =

| boxbgcolor =

| image = Marthozite-jr-6b.jpg

| imagesize = 260px

| caption = Marthozite crystals in a vug, from Katanga (size: 6.2 x 5.3 x 4.0 cm)

| formula = Cu(UO₂)₃(SeO₃)₃(OH)₂·7H₂O

| IMAsymbol = Mhz{{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}}

| molweight = 1,303.67 g/mol

| strunz = 4.JJ.05

| system = Orthorhombic

| class = Pyramidal (mm2)
(same H-M symbol)

| symmetry = Pbn2₁

| unit cell = a = 16.4 Å, b = 17.2 Å,
c = 6.98 Å; Z = 4

| color = Greenish brown

| habit = Bladed

| twinning =

| cleavage = {100} perfect, {010} indistinct

| fracture =

| tenacity =

| mohs = 6

| luster =

| refractive = 1.780–1.800

| opticalprop = Biaxial (−)

| birefringence =

| dispersion = Extreme

| pleochroism = Yellowish brown to greenish yellow

| 2V = 39°

| streak =

| gravity = 4.44

| density =

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity =

| other = 25px Radioactive

| references = [https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Marthozite Mineralienatlas][http://webmineral.com/data/Marthozite.shtml Webmineral data][http://www.mindat.org/min-2582.html Mindat.org]{{Cite web |url=http://www.handbookofmineralogy.com/pdfs/marthozite.pdf |title=Handbook of Mineralogy |access-date=2010-12-13 |archive-date=2021-07-23 |archive-url=https://web.archive.org/web/20210723102459/http://www.handbookofmineralogy.com/pdfs/marthozite.pdf |url-status=dead }}

}}

Marthozite is an orthorhombic mineral that has a general formula of Cu(UO₂)₃(SeO₃)₃(OH)₂·7H₂O. It was named after Belgian mineralogist Aimé Marthoz (1894–1962), former Director-general of the Union Minière du Haut Katanga (UMHK).

It is usually found in cavities in selenian (selenium-containing) digenite. It is specifically found in the zones of oxidation of the Musonoi deposit in Katanga, Africa.Fleischer, M. (1970) New mineral names. American Mineralogist, 55, 533.

Marthozite is orthorhombic, meaning that it has three axes of unequal lengths all orthogonal to each other. Since it is orthorhombic, marthozite is biaxial, meaning that it has three different indices of refraction. Marthozite is anisotropic, which means that it breaks light into one fast ray and one slow ray.{{Cite web|url = http://www.wolframalpha.com/entities/minerals/marthozite/u7/vh/op/|title = Marthozite|accessdate = 5 June 2019}}{{Dead link|date=April 2023 |bot=InternetArchiveBot |fix-attempted=yes }} Marthozite shows pleochroism from yellowish brown to greenish yellow.