liroconite

{{short description|Copper aluminium arsenate mineral}}

{{Infobox mineral

| name = Liroconite

| boxwidth =

| boxbgcolor =#278aa0

| boxtextcolor = #fff

| image = Liroconite-Strashimirite-171815.jpg

| imagesize = 260px

| alt =

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| category = Arsenate minerals

| formula = Cu₂Al[(OH)₄|AsO₄]·4(H₂O)

| IMAsymbol = Lro{{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 =

| strunz = 8.DF.20

| dana =

| system = Monoclinic

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = I2/a

| unit cell = a = 12.66, b = 7.57
c = 9.89 [Å]; β = 91.25°; Z = 4

| color = Bright blue to green

| colour =

| habit = Typically as striated flattened octahedral or lenticular crystals, also massive to granular

| twinning =

| cleavage = Indistinct on {110} and {011}

| fracture = Irregular/uneven, conchoidal

| tenacity =

| mohs = 2–{{frac|2|1|2}}

| luster = Vitreous to resinous

| streak = Light blue

| diaphaneity = Transparent, translucent

| gravity = 2.9–3

| density =

| polish =

| opticalprop = Biaxial (−)

| refractive = n_α = 1.612 n_β = 1.652 n_γ = 1.675

| birefringence = δ = 0.063

| pleochroism =

| 2V = Measured: 67°

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| references = [http://www.mindat.org/min-2413.html Mindat.org: Liroconite mineral information and data][http://www.webmineral.com/data/Liroconite.shtml Webmineral data][http://rruff.geo.arizona.edu/doclib/hom/liroconite.pdf Handbook of Mineralogy]

}}

Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu₂Al[(OH)₄|AsO₄]·4(H₂O). It is a vitreous monoclinic mineral, colored bright blue to green, often associated with malachite, azurite, olivenite, and clinoclase. It is quite soft, with a Mohs hardness of 2–2.5, and has a specific gravity of 2.9–3.0.

File:Liroconite-Clinoclase-120699.jpg lined with lustrous, blue-green liroconite blades and sparkly, dark blue clinoclase microcrystals from Wheal Gorland (size: 3.4 × 3.0 × 2.0 cm)]]

It was first identified in 1825 in the tin and copper mines of Devon and Cornwall, England. Although it remains quite rare it has subsequently been identified in a variety of locations including France, Germany, Australia, New Jersey and California.

The type locality for liroconite is Wheal Gorland in St Day, Cornwall in the United Kingdom. The largest crystal specimen on public display is in the Royal Cornwall Museum in Truro.{{cite web |title=Liroconite |last=Aubrey-Jones |first=David |date=2008 |url=http://britishrocks.com/}}

It occurs as a secondary mineral in copper deposits in association with olivenite, chalcophyllite, clinoclase, cornwallite, strashimirite, malachite, cuprite and limonite.