Dresser Trap Rock Quarry, Polk County, Wisconsin

Dresser Quarry

Dresser Quarry, Polk County, WI

LOCATION: Sec. 5 and 6 T.33N. R.18W, near Dresser.

ACCESSIBILITY: Working quarry - private property.

GEOLOGY: Keweenawan lava flows, metamorphosed to the greenschist facies, cross-cut by quartz veins. Basalt coarsens to a gabbro pegmatite towards the middle of the thickest flows.


Actinolite - fine-grained in metabasalt matrix and amygdules.
Augite - primary igneous material, in phenocrysts. up to 1 cm. across in the basalt and elongated xls. up to 3 cm. long in the gabbroic lenses. Often altered to metamorphic minerals.
Bornite - sparse, in veins and amygdules.
Calcite - flat rhombohedral white to pale yellow crystals and cleavable masses in veins.
Chalcocite - sparse massive in quartz veins.
Chalcopyrite - sparse in amygdules and quartz veins.
Chlorite -abundant in metabasalt matrix, amygdules and veins.
Chrysotile - long fibers along joint surfaces.
Copper - reported massive in flow tops and in amygdules.
Cuprite - sparse massive in quartz veins.
Epidote - massive material abundant in metabasalt matrix, and as crystals and clusters in amygdules and along veins.
Hematite - massive in amygdules and as coatings.
Ilmenite - masssive in metabasalt and gabbro pegmatite.
Magnetite- masssive in metabasalt and gabbro pegmatite.
Malachite - massive coatings and tiny botryoidal masses in vugs in quartz veins.
Potassium Feldspar - red to orange massive in amygdules, also drusy pale pink to cream xls. on quartz
Plagioclase feldspar - primary igneous material in the basalt the gabbroic lenses. Generally much altered to secondary metamorphic minerals.
Quartz - as massive white quartz in thick veins, locally opening into vugs with xls. up to 10 cm. long. Also in amygdules.
Tremolite - long fibers along joint surfaces with calcite.
Zoisite - replacing plagioclase.


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