Secondary minerals such as calcite, epidote, quartz or talc can precipitate from the circulating groundwater filling the voids and cementing the rock.
en.wikipedia.org It is found in association with tremolite, quartz, epidote, monazite, copper, cuprite, atacamite, buttgenbachite, malachite, paratacamite, and anthonyite.
en.wikipedia.org A contact aureole of 2.5 km thickness surrounds the batholith in the form of albite epidote hornfels.
en.wikipedia.org The crystallographic and optical characters are similar to those of epidote; the pleochroism is strong with reddish-, yellowish-, and greenish-brown colors.
en.wikipedia.org Quartz crystals make up 25%, plagioclase 5%, alkali feldspar 10%, biotite 5-10% which is altered to chlorite, epidote and leucoxene.
en.wikipedia.org