Don,
It certainly can, but there is no single process which is suitable for all types of specimens. I made MANY (>1000) thin sections when I worked for the
BGS, using a variety of rotary & vibrating laps, with various abrasives and lubricants.
The choice of techniques to use during the various stages of making the sections (all rotary lapping / R & vibrating / all V /; which lap surface, rotary speed or vibration frequency, which specimen holder, weights, and which lubricants and abrasive materials to use, particularly for the final stages, as the section thickness gets below about 100um) was determined by a number of variables. Obviously, in the first instance, the type of specimen and its robustness (range of hardness of the components, easy cleavage or abundant fractures, and any degradation by reaction with polishing media etc. For instance, making a section of a rock containing halite, would obviously mean that contact with water would need to be avoided at all stages of course, but there are more subtle effects to consider also. (e.g. an apparently well-indurated tuff with incipient weathering, might have some montmorillonite present which was insufficient to cause problems in the early sawing & grinding stages, but would cause the section to fall apart towards the end of the lapping process - very frustrating!)
A crumbly shelly limestone, a bentonite, a coarse garnetiferous mica schist, granite, etc etc, would each require different approaches to the preparation schemes at some stages, and the type of section required will also need to be taken into consideration. (e.g. an oriented section of a single crystal for demonstrating the optical properties, or a polished section of mineral vein with soft sulphides in quartz for viewing the opaque phases in incident light, will be trickier subjects than a conventional TS of a randomly oriented slice of fine-grained fresh basalt.)
Back to basics though: assuming you are not wanting a highly specialised end product, such as double-polished sections for fluid inclusion studies, or an ultra-high polish for microprobe analysis, but simply a standard thin section for optical microscopy/petrography & photograhy of rock textures, mineral pleochroism, etc. There is a good synopsis of standard TS preparation tequniques
HERE, and you will find some clues as to the technology
HERE, and I am sure you would be able to get some good results with a vibrating lap.
The question that then arises is one of buget. If cash is no problem, there are many high-tech machines available from companies such as
Buehler,
Struers &
Logitech (Not the same company that makes PC acessories!), but the cost of those runs to many 1000's of £/$. However if you are willing and able to do a bit of home machine-building, it is possible to make something pretty effective; I have seen home-made vibrating laps which were driven by mounting the lap on a stub coupled to the outer sleeve of a ball-race, with the shaft at the centre of a the ball-race coupled to the spindle of a slightly off-centred motor by a short length of rubber tubing! (The amplitude of the vibrations could be adjusted by varying the off-set of the motor.)
Of course, it is always worth keeping an eye open for second-hand equipment; I was very fortunate to acquire an earlier model of the
Struers Accutom (the Mk2) for a bargain price at a mineral show a few years ago. I have only used it a few times, and it doesn't quite finish the sections, but at least it gets them thin enough that only the last bit of finishing needs to be done by hand on the glass plate.
There is a detailed brochure of the Struers Accutom 5
HERE which is a much more advanced bit of kit than my old Mk2 (and looks like it theoretically DOES get down to a finished section thickness.) It's worth having a look at for a bit more technical info on sectioning.
Pete N.
Eds for sp, to remove repetition, & add a couple of notes
Edited 4 time(s). Last edit at 01/19/2008 01:14PM by Peter Nancarrow.
