mellite

{{Infobox mineral | name = Mellite | boxwidth = | boxbgcolor =#7c5745 | boxtextcolor = #fff | image = Mellite-177555.jpg | imagesize = 260px | alt = | caption = | category = Organic minerals | formula = Al2[C6(COO)6]·16H2O | IMAsymbol = Mel | molweight = | strunz = 10.AC.05 | dana = | system = Tetragonal | class = Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) | symmetry = I41/acd | unit cell = a = 15.53 Å, c = 23.19 Å; Z = 8 | color = Honey-yellow, deep red, pale shades of red, brown, gray, white; | colour = | habit = Elongated bipyramidal prismatic; as nodules and coatings, fine-grained massive | twinning = | cleavage = poor/indistinct on {023} | fracture = conchoidal | tenacity = Slightly sectile | mohs = 2– | luster = Vitreous, resinous, greasy | streak = White | diaphaneity = Transparent to translucent | gravity = 1.64 | density = | polish = | opticalprop = Uniaxial (−) may be anomalously biaxial | refractive = nω = 1.539 nε = 1.511 | birefringence = δ = 0.028 | pleochroism = Weak; O = yellowish brown; E = yellow | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = Pale yellow to blue (LW & SW UV) | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = Pyroelectric | prop1 = | prop1text = | references = }}

Mellite, also called honeystone, is an unusual mineral being also an organic chemical. It is chemically identified as an aluminium salt of mellitic acid, and specifically as aluminium benzenehexacarboxylate hexadecahydrate, with the chemical formula Al2C6(COO)6·16H2O.