The axinite group includes:
axinite-(Fe):
Ca4Fe2+2Al4[B2Si8O30](OH)2
axinite-(Mg):
Ca4Mg2Al4[B2Si8O30](OH)2
axinite-(Mn):
Ca4Mn2+2Al4[B2Si8O30](OH)2
tinzenite:
Ca2Mn2+4Al4[B2Si8O30](OH)2
All of these are triclinic sorosilicates (Si2O7 groups)
Localities
At Heng Fa Chuen, Hong Kong Island, Hong Kong, China, axinite occurs in a
pegmatite at the Chai Wan MTR (Mass Transit Railway) railway depot, just
southeast of the Heng Fa Chuen MTR station, adjacent to the eastern entrance of the MTR railway tunnel. The
pegmatite cavity occurs in medium-grained
granite almost completely devoid of
biotite.
About 20 m away the contact of granite with pyroclastic rocks is exposed.
The pegmatite cavity is about 40 cm wide and contains axinite,
K-feldspar, milky quartz and
muscovite
(Geological Society of Hong Kong newsletter 2.1.9).
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