December 3, 2010

Goniometers

I am the proud owner of a Stoe optical goniometer.

It is labeled "Stoe, Heidelberg, Made in Germany". All inscribed in English. "Type 64015".
Another label proudly states, "Made in West Germany".

I purchased this at the University of Arizona surplus auction sometime prior to (or around) 2010. I don't remember what my winning bid was, but it was something on the order of $200.

To make use of it, I needed a goniometer head. I found one on Ebay for a good price (perhaps $80, but I have forgotten). The bargain was because it was "broken". I gambled that I could fix it, and I won. The problem was just old grease. Once I took it apart, cleaned off the old grease with xylene, and put it back together with some new grease it works just fine.

Time marches on

Crystallography these days is all about crystal structures. Nobody is much interested in measuring the angles of crystal faces. This instrument was maintained by the geosciences department simply because it was used to orient crystals that were then taken to a precession or weissenberg camera to collect X-ray diffraction data.

Even those instruments are now obsolete. New X-ray diffraction machines have computer software that can orient crystals as long as they are simply centered in the beam. For this reason, they also no longer need goniometer heads with rotation arcs. The machine can manage the angular rotations, the head just needs to have translations to center the crystal.

Oryctics

This is a google group devoted to historical crystallography and mineralogy that is a source of information about goniometers (and other things).
To subscribe, visit this link: which will bounce you on to google groups. I have spent no time on this group and cannot vouch for it or whether it even still exists. People love to collect these old instruments, particularly even older ones than the Stoe I have that were works of art made from brass. I am more utilitarian.
Feedback? Questions? Drop me a line!

Tom's Mineralogy Info / [email protected]