Sulphide, nickel-bearing mineral
Specific gravity: 5.82
Streak: Light bronze
Colour: Light bronze or brass yellow
Common impurities: Fe
in serpentinised dunite and lherzolite, where it is probably of hydrothermal origin;
in layered mafic intrusives and chromitite, where it may be a low-temperature secondary mineral;
in mantle xenoliths.
Associated minerals include andradite, pentlandite, serpentine, chalcopyrite, violarite, cubanite, millerite, mackinawite, orcelite, zaratite, shandite, awaruite, platinum group minerals, magnetite and chromite (HOM, Mindat).
At the type locality, the Lord Brassey mine, Heazlewood district, Waratah-Wynyard municipality, Tasmania, Australia, heazlewoodite occurs intergrown with magnetite in a band in serpentine. A very small amount of pentlandite was present, and the surface of the heazlewoodite was coated with zaratite (AM 32.484).
At the Alexo Mine, Dundonald Township, Timmins, Cochrane District, Ontario, Canada, heazlewoodite occurs in the serpentinised peridotite hanging wall of the old nickel mine. The heazlewoodite occurs as very small yellowish cream grains, in most cases less than 0.02 mm in diameter.
Pyrrhotite and pentlandite are the principal sulphides of the ore zone, and magnetite and very minor amounts of chalcopyrite are also present. Heazlewoodite is restricted to the peridotite of the hanging wall and co-exists with no sulphide other than pentlandite. It is sparsely distributed, never exceeding 0.25 per cent in amount (CM 8.383-385).
In serpentinites of the Eastern Townships, Quebec, Canada, magnetite occurs as threads between ghost olivine or pyroxene crystals as discrete grains, or as rims around primary chromite crystals. It is invariably in contact with serpentine and commonly associated with either heazlewoodite or awaruite. Heazlewoodite is a common minor constituent of the serpentinites, with an average grainsize of about 30 microns. Heazlewoodite was not observed in the same sections with awaruite, but it accompanies magnetite in most of the sections in which it occurs. It is suggested that heazlewoodite and magnetite formed contemporaneously as by-products of the serpentinisation process and that they represent an equilibrium assemblage. Nickel already present in the rocks almost certainly accounts for the nickel in the heazlewoodite (CM 8.519-522).
At Miles Ridge, Whitehorse mining district, Yukon, Canada, heazlewoodite is associated with granular pentlandite. Both minerals are embedded in a spongy mass of magnetite. The metallic minerals form a veinlet in green serpentine-like gangue with disseminated magnetite. The minerals occur in a short stringer of sulphides on the lower contact of a serpentinised peridotite dyke, about 200 feet wide and several miles long, which cuts a series of silicified tuff and limestone. The rocks near the veinlet are brecciated and strongly altered to serpentine and carbonates (AM 40.692-693).
At the Belvidere Mountain Quarries, Lowell & Eden, Orleans & Lamoille counties, Vermont, USA, heazlewoodite occurs as pale brass-yellow grains containing minor cobalt, iron and magnesium, and it is a primary mineral in the dunite, in which it is embedded along with many bands and inclusions of magnetite (R&M 90.6.538-539).
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