Australian Facetors' Guild Limited

I am trying to cut a piece of this material and boy is it hard there is another material with a similar name that has a hardness of 8 but this is much harder and was found in AU. it double refracts and polished like topaz only brighter the problem I have is the very fine scratches that appear in the window I have recut the facets several times now in an attempt to remove the scratches but they persist. any help with this will be appreciated.

Ron

I've never cut Phenakite but the mention of twinning and the problem with scratching is reminiscent of issues I have encountered with twinned quartz.  Bob Kelly first alerted  me to it due to Quartz being brittle.  Broadfoot and Collins at page 240 mentions some issues with brittleness.

I overcame the problems with quartz by cutting using water as a lubricant and polishing with a Linde A lightning lap.  An Aluminium oxide ceramic lap with no diamond and water as a coolant should also work.

I postulate that the water acts as a superior coolant when cutting as water can adsorb 4 times  the heat oil can adsorb.

Using water as a coolant seems to stop the little pieces breaking away from the surface of quartz to cause the scratches.  It also flushes the swarf away, reducing another potential source of scratching.  

However, I've also found that CZ cuts with less scratches using oil as a lubricant than when using lightning laps with water.  So you may need to experiment a bit.