duftite

{{short description|Arsenate mineral}}

{{Infobox mineral

| name = Duftite

| category = Arsenate minerals

| boxwidth =

| boxbgcolor =

| image = Anglesite-Duftite-174037.jpg

| alt =

| caption = Duftite from Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia

| formula = PbCuAsO₄(OH)

| IMAsymbol = Dft{{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 = 426.67 g/mol

| strunz = 8.BH.35

| dana = 41.5.1.4

| system = Orthorhombic

| class = Disphenoidal (222)
H-M symbol: (2 2 2)

| symmetry = P2₁2₁2₁

| unit cell = a = 7.768(1), b = 9.211(1)
c = 5.999(1) [Å]; Z = 4

| color = Green, olive green or grey green. Generally zoned due to compositional variations.

| habit = Tiny crystals elongated along [001] with curved and rough faces, aggregated into crusts. Crystals may be pseudo-octahedral.

| lattice =

| twinning =

| cleavage = Indistinct

| fracture = Uneven to conchoidal

| tenacity =

| mohs = 4.5

| luster = Vitreous on fracture surfaces and dull on crystal faces

| refractive = n_α = 2.03–2.04, n_β = 2.06–2.08, n_γ = 2.08–2.10

| opticalprop = Biaxial (-), faint apple-green color (transmitted light)

| birefringence = δ = 0.06

| pleochroism =

| 2V = Large

| dispersion = r > v, perceptible

| streak = Pale green or white

| gravity = 6.4 (measured), 6.60 (calculated)

| density =

| melt =

| fusibility =

| diagnostic =

| solubility = Readily soluble in acids

| diaphaneity = Crystals are transparent to translucent

| other = Decrepitates on heating. Not radioactive.

|references = [http://www.webmineral.com/data/Duftite.shtml Duftite]. Webmineral.com. Retrieved on 2011-10-10.[http://www.mindat.org/min-1325.html Duftite]. Mindat.org[http://rruff.geo.arizona.edu/doclib/hom/duftite.pdf Duftite]. (PDF) Handbook of Mineralogy

}}

Duftite is a relatively common arsenate mineral with the formula CuPb(AsO₄)(OH), related to conichalcite. It is green and often forms botryoidal aggregates. It is a member of the adelite-descloizite Group, Conichalcite-Duftite Series. Duftite and conichalcite specimens from Tsumeb are commonly zoned in color and composition. Microprobe analyses and X-ray powder-diffraction studies indicate extensive substitution of Zn for Cu, and Ca for Pb in the duftite structure. This indicates a solid solution among conichalcite, CaCu(AsO₄ )(OH), austinite, CaZn(AsO₄)(OH) and duftite PbCu(AsO₄)(OH), all of them belonging to the adelite group of arsenates.{{cite journal|url=http://rruff.info/uploads/CM18_191.pdf|author=Jambor, J L, Owens, D R and Dutrizac, J E |year=1980|title= Solid solution in the adelite group of arsenates|journal= Canadian Mineralogist |volume=18|pages= 191–195}} It was named after Mining Councilor G Duft, Director of the Otavi Mine and Railroad Company, Tsumeb, Namibia.{{cite journal|vauthors=Wherry ET, Foshag WF|year=1921|title=New mineral names|journal= American Mineralogist |url=http://www.minsocam.org/ammin/AM6/AM6_140.pdf|volume=6|pages= 140–141}} The type locality is the Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia.