One reason for this may be that metabasites are messy. Grain size is often too small to make positive identification, and many minerals have anhedral, fibrous, or massive habits, unlike the distinct forms common among other metamorphic rocks.
More text coming here.
You don't need an expensive microscope to view thin sections in cross-polarized light. I made my own polarizing microscope a few years ago, when I started grad school. The microscope in the photo is a $200 Observer. I bought a couple of polarizing filters for $20 each, and made a platform for the polarizer out of cardboard. That's my old Pentax film camera in the photo. I now use a Pentax digital SLR. One more thing - the microscope adapter cost $125. Total investment (assuming you have a suitable camera and tripod): $365. I used this setup to make all of the photomicrographs on this blog. I now have a "real" polarizing microscope - a Meiji ML9300 trinocular - but I still use this primitive apparatus for all of my photomicrographs.
Picture above.
