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Formula: NaMg3(Si3Al)O10(OH)2
Phyllosilicate (sheet silicate), trioctahedral mica group,
mica group
Crystal system: Monoclinic
Specific gravity: 2.885 calculated
Hardness: 2 to 3
Streak: White
Colour: Light brown, white, greenish red
Environments
Aspidolite occurs in thermally metamorphosed rocks
( greenschist to
amphibolite facies) in the contact aureole of
granite
(HOM).
Localities
There are two co-type localities, Zillertal, Schwaz District, Tyrol, Austria, and Kasuga mine, Ibigawa-cho, Ibi
District, Gifu Prefecture, Japan.
At El Mourdur Hill, Derrag, Aziz District, Médéa Province, Algeria, aspidolite occurs in metamorphosed
evaporite rocks
(HOM)
At San Pedro volcano, Maule, Chile, aspidolite has been found in
gabbroic norite
xenoliths
(HOM).
In the North Qilian Mountains, Qinghai, China, aspidolite has been found as inclusions in
chromites of mafic layered intrusions and
ophiolite complexes. Associated minerals include
enstatite and spinel
(HOM).
At Kasuga mine, Ibigawa-cho, Ibi District, Gifu Prefecture, Japan, aspidolite occurs in
hornfels from a contact aureole, interleaved with and surrounded by
phlogopite. The
aspidolite-phlogopite assemblage is associated with
amphibole (pargasite -
sadanagaite),
titanite, calcite,
scapolite, apatite,
pyrrhotite and
chalcopyrite. The
phlogopite rim is interpreted as a later product, probably formed
metasomatically
(MM 69.6.1047-1057).
Aspidolite from Kasuga Mine -
Image
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