Sample Selection | Sectioning | Epoxy Mounting | Grinding & Polishing | Etching | Microscopy
of metals and other opaque minerals
requites the use of reflected-light
The Polyvar microscope manufactured by Reichert-Jung
and Leica is
considered by many to be the "Rolls Royce"
of microscopes. I own a Polyvar-SC equipped with
both reflected and transmitted-light
illumination. The "supermodule"
slider allows easy transitioning between
brightfield, polarized, and darkfield
modes. The microscope is also
equipped with differential interference
contrast (DIC, also known as Nomarski),
and this mode of
illumination is effective in amplifying
minor topographic variations of the
following images show a troilite
inclusion in the iron meteorite NWA6259, viewed using the
three modes of reflected-light
illumination (FOV = 688 microns).
The photo on the left was taken in plane-polarized
light and shows troilite nodule
surrounded by cloudy zone taenite. The thin
white mineral at the top of the troilite is schreibersite (isotropic). The
center photo, taken in
cross-polarized light, reveals
the presence of troilite twinning.
The third photo was taken using
differential interference contrast.
For reflected-light work,
it is important that the
specimen's surface is precisely
perpendicular to the microscope
objective. This can be
accomplished using a metallographic
specimen press (shown next to the
microscope in the top photo).
Plasticine is sandwiched between the
specimen and glass slide, and the press
assures parallelism between the glass
slide and specimen.
For photography, I use a Canon T3i
coupled to the microscope using a Zeiss
camera adapter of 0.25x magnification
(Zeiss # 45 60 29) and Wild-Herzburg
eyepiece of 5x. This
combination yields a total camera adapter magnification
of 1.25x. The Canon T3i is an excellent
choice for microscopy because it has "Liveview"