Massive Zn-Cu-Fe sulfide deposits at the Garon Lake Mine occur in three
sulfide lenses in a group of metamorphosed rhyolite crystal tuffs, metasediments
and basalts. The major ore minerals are sphalerite, chalcopyrite, pyrrhotite and
pyrite. Minor associated silicates are actinolite, tremolite, chlorite, albite and
quartz. Rounded detrital pyrite, magnetite and chert grains and diagenetic pyrite
are the only preseved premetamorphic features. Middle amphibolite facies
regional metamorphism is marked by sulfide-silicate foliation, and syntectonic
porphyroblasts of pyrite. After the intrusion of a granodiorite pluton, pyrite was
fractured, and the other sulfides developed wedge-shaped twins. These minerals
were subsequently involved in porphyroblasitic and polygonal granoblasticgrowth
and annealing. Cordierite and anthophyllite developed fromchloritized wallrocks.
During retrograde changes, some pyrrhotite wasconverted to pyrite, marcasite and
magnetite. On the evidence of textures and mineralogy, the deposit is
synsedimentary-diagenetic and of distal type