CL image of a sulfide-calcite veinlet cutting altered andesitic hornfels.

Brilliant yellow orange CL is calcite (Mn+2 activation). Grains with lemon yellow CL are apatite (also Mn+2 activation). K-spar exhibits light blue CL. The orange red CL is a calcite with different activators/quenchers.

Photo courtesy of Jim Clark and AMT (USA) Inc. Jim Clark, Applied Petrographics, Portland, OR.

For a larger view, click on the corresponding photo.

andeistic hornfels