Steatitization of serpentinite bodies in north-central Vermont

The talc deposits of north-central Vermont are associated with bodies of ultramafic rock, chiefly serpentinite, that are enclosed by metamorphosed sedimentary and volcanic rocks of Cambrian and Ordovician age; these stratified rocks form an essentially homoclinal succession in the east limb of the Green Mountain anticlinorium. The rocks at the localities described here are in the greenschist facies, and show only slight variations in grade of metamorphism between localities.

The talc deposits consist typically of a core of serpentinite surrounded by successive shells of talc-carbonate rock and of steatite, next to which the country rock is altered for several inches to chlorite rock (blackwall). The steatite zone is rather uniformly about 3 feet thick, but the talc-carbonate rock and serpentinite zones vary considerably in thickness and are locally very irregular.