187 - Sodalite

ID	187
Mineral	Sodalite
Location	Ontario - Canada
Fluorescence	LW-UV: close SW-UV: close
Mindat.org	View Sodalite information at mindat.org

ID	3701
Long ID	1:1:3701:9
Formula	`Na₄(Si₃Al₃)O₁₂Cl`
IMA Status	0 1
Occurrence	Nepheline Seyenite
Other Occurrences	Sodalites occur: - in alkaline intrusives (Princess Mine, Bancroft, Ontario, Canada); - in alkaline pegmatites (Mont St Hilaire, Quebec, Canada); - in carbonatites (Magnet Cove, Arkansas, USA); - in marble skarns or metasomatized calcareous rocks (Ladjuar Medan, Sar-e-Sang, Afghanistan); - in phonolites and volcanic ejecta (Mount Vesuvius, Italy).
Discovery Year	1811
Diapheny	Transparent,Translucent
Cleavage	Poor on {110}
Tenacity	brittle
Colour	All Colours
Hardness (min)	5.5
Hardness (max)	6.0
About the name	The name reflects its sodium content.
Streak	White
Crystal System	Isometric
Cleavage Type	Poor/Indistinct
Fracture type	Sub-Conchoidal
Morphology	Crystals rare, dodecahedron.
Twinning	Common on {111} forming pseudohexagonal prisms. (This may not be twinning, but merely elongated growth in the (111) direction). Twinning can occur in these elongated crystals. These have re-entrants in the terminations and 6 terminal faces instead of 3 for an elongated dodecahedron.
UV	Bright red-orange under SW UV and blue, white, pink, red, yellow LW UV. Cathodoluminescent (the effect is quenched by high concentrations of S, as shown by Zahoransky et al., 2016). Yellowish phosphorescence may be photochromic in magentas.
Publication Year	1811
key_elements	0
shortcode_ima	Sdl
Group	Sodalite Group

Sodalite