Formula: Cu9S8
With oxidation states Cu1+20Cu2+7(S2)2-7S2-10 (CM 23.61-76)
Sulphide, chalcocite-digenite group, forms a series with chalcocite
Specific gravity: 4.89 calculated
Hardness: 2½
Colour: Bluish grey, black
Common impurities: Fe,Ag

Hydrothermal environments

Yarrowite is commonly associated with anilite, bornite, chalcopyrite, covellite, digenite, djurleite, idaite, tennantite and wittichenite (Mindat).


At the type locality, Yarrow Creek, Yarrow Creek-Spionkop Creek deposit, Alberta, Canada, yarrowite occurs as a replacement of other copper sulphides by selective removal of copper. Yarrowite also replaces spionkopite and copper-iron sulfides. At the deposit copper-bearing sulphides include chalcopyrite, bornite, spionkopite, yarrowite, digenite, djurleite, idaite, wittichenite and tennantite. Near-surface leaching of copper from the natural specimens produced the following changes:
djurleite to anilite + Cu(aq) to spionkopite + Cu(aq) to yarrowite + Cu(aq) to covellite (minor) + Cu(aq) (CM 18.511-518).

At the Clargillhead vein, Garrigill, Alston Moor, Eden, Cumbria, England, UK, yarrowite occurs as crystals less than 1 micron in size, accompanied by similar sized zones of heavily tarnished unidentified blue copper sulphides, interbanded with cerussite, some of which is associated with an unidentified silver-bearing photosensitive phase. Spionkopite occurs as rare grains in cerussite and also in association with tarnished copper sulphides (JRS 23.51).

At Rassal, Loch Kishorn, Highland, Scotland, UK, yarrowite occurs as a blue-grey to deep blue coarse flakes in goethite. Associated minerals include covellite and spionkopite (JRS 15.56).

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