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Formula: Mg5Al11TiO23(OH)
Oxide, högbomite group,
titanium-bearing mineral
Crystal System: trigonal
Specific gravity: 3.87 calculated
Hardness: 6½
Streak: Brown
Colour: Dark brown to black
Environments
Magnesiohögbomite-6N 12S is a relatively new mineral, approved in 2020 and to date (April 2022) reported only from the type
locality.
Localities
At the type locality, Lot 10, Concession 1, Dewitts Corners area, Bathurst Township, Lanark County, Ontario, Canada, the new
högbomite-group mineral magnesiohögbomite was found in
calcite “vein-dikes”. It forms tabular and short-prismatic crystals up to 5 mm in size.
The associated minerals are magnesiohögbomite-2N 3S,
spinel, corundum,
diopside, magnesio-hastingsite,
pargasite, clinochlore and
calcite
(MM 85.3.398-405).
The deposit is
located in the Grenville Geological Province, which consists mostly of
marble, gneiss, and
quartzite.
Syenite-migmatite was
also reported in the area where the vein-dikes are located. Characteristic features of the vein-dikes include the
fact that perfectly formed euhedral crystals of different minerals can often be found floating in
calcite with no points of contact with the walls. Sometimes these crystals
have inclusions of calcite, irregular or rounded in shape. It has been argued
that at least some of the vein-dikes were formed as a result of melting of Grenville
marble
(R&M 97.6.556-564).
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