Fluorcanasite

(repeating unit)K₃Na₃Ca₅Si₁₂O₃₀F₄•H₂OStrunz classification09.DG.80Dana classification78.05.04.02Crystal systemMonoclinicCrystal classDomatic (m)Space groupBmUnit cell1,602.59 ųIdentificationFormula mass1,297.67 gmColorLight YellowCleavageEminent on {100} and {201}
Perfect on {001}FractureHackly, Step-likeTenacityBrittleMohs scale hardness5LusterVitreousStreakWhiteDiaphaneityTransparentSpecific gravity2.68DensityMeasured 2.68(2)
Calculated 2.69Optical propertiesBiaxial (+)Refractive indexn_α = 1.538(1)
n_β = 1.546(1)
n_γ = 1.549(1)Birefringence0.011PleochroismStrong2V angleMeasured 60° (2)
Calculated 63°DispersionMedium
r > vUltraviolet fluorescenceNoneSolubilitySlowly decomposes in acidOther characteristics Radioactive 0.77% (K)

Fluorcanasite is a rare calcium, potassium, sodium fluoride silicate mineral, discovered in the Kirovsk mine's dumps, in Russia. It has been approved by the IMA in 2007. The name fluorcanasite is a portmanteau word, and was made by blending fluorine, a chemical element that can be found in the mineral, and canasite, as the mineral is close to canasite in several ways (analogue of said mineral and a member of the canasite group). Fluorcanasite is also close to frankamenite.^[1]

It is the triclinic analogue of canasite, and a member of the canasite group. It grows into prismatic crystals that can reach up to 2 mms in size extending along [010]. It is pleochroic, meaning the color of the mineral seems to change depending on the axis it is viewed at. It is coloured amber, purple and lilac respectively along the α, β and γ optical axes.^[1] It has a barely detectable 0.77% potassium radioactivity measured by the GRapi (Gamma Ray American Petroleum Institute Units). It consists mostly of oxygen (38.22%), silicon (25.97%) and calcium (15.44%), but otherwise contains potassium (9.04%) - which gives its radioactive attributes - fluorine (5.86%) and sodium (5.31%).^[2] Parting is parallel to {001}. Hackly fracture only applies on the b axis, among a and c axis the fracture is stepped.^[3]

Fluorcanasite is a type locality at Mount Kukisvumchorr, Russia.^[2] It is associated with pectolite, microcline, nepheline, villiaumite, scherbakovite, rasvumite, lamprophyllite, mosandrite, molybdenite and aegirine.^[1]