Fluorcanasite
General
Category	Mineral
Formula (repeating unit)	K3Na3Ca5Si12O30F4•H2O
Strunz classification	09.DG.80
Dana classification	78.05.04.02
Crystal system	Monoclinic
Crystal class	Domatic (m)
Space group	Bm
Unit cell	1,602.59 ų
Identification
Formula mass	1,297.67 gm
Color	Light Yellow
Cleavage	Eminent on {100} and {201} Perfect on {001}
Fracture	Hackly, Step-like
Tenacity	Brittle
Mohs scale hardness	5
Luster	Vitreous
Streak	White
Diaphaneity	Transparent
Specific gravity	2.68
Density	Measured 2.68(2) Calculated 2.69
Optical properties	Biaxial (+)
Refractive index	nα = 1.538(1) nβ = 1.546(1) nγ = 1.549(1)
Birefringence	0.011
Pleochroism	Strong
2V angle	Measured 60° (2) Calculated 63°
Dispersion	Medium r > v
Ultraviolet fluorescence	None
Solubility	Slowly decomposes in acid
Other 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]

Properties

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]

Occurrences and localities

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]

References