The white calcite veins don't stand out well against the light clays of the altered volcaniclastic rocks, so I've highlighted a few patches below.
There's one large vein here, but myriads of smaller ones, ranging from a couple millimeters to maybe a centimeter or two. The calcite was emplaced into what appear to be faults; many show casts of slickensides. However, the rock itself is too rotted to be able to identify offsets or slicks in place. Only the mineralization hints at their existence.