hydroboracite

{{Infobox mineral

| name = Hydroboracite

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| image = Hydroboracite-471230.jpg

| imagesize = 260px

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| category = Inoborates

| formula = CaMgB₆O₈(OH)₆·3H₂O

| IMAsymbol = Hbo{{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 = 6.CB.15

| dana =

| system = Monoclinic

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

| symmetry = P2/c

| unit cell = a = 11.76, b = 6.68
c = 8.23 [Å]; β = 102.59°; Z = 2

| colour = Colourless, white

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| mohs = 2

| luster = Vitreous, silky

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| diaphaneity = Transparent

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| opticalprop = Biaxial (+)

| refractive = n_α = 1.520 – 1.523 n_β = 1.534 – 1.535 n_γ = 1.569 – 1.571

| birefringence = δ = 0.049

| pleochroism =

| 2V = Measured: 60° to 66°, calculated: 62° to 66°

| dispersion = Relatively weak

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| solubility = Very poorly soluble in cold water. Partially dissolved by prolonged submersion in boiling water.

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| references = [http://webmineral.com/data/Hydroboracite.shtml Webmineral data][http://www.mindat.org/min-1967.html Mindat]

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Hydroboracite is a hydrated borate mineral (hence the name) of calcium and magnesium, whose chemical composition is CaMgB₆O₈(OH)₆·3H₂O. It was discovered in 1834 in the Inder lake, Atyrau Province, Kazakhstan. Hydroboracite is a minor borate ore mineral.