re polishing basalt

["Will Johnson" <willj@zzzzzzzzzzz>]

In my area (central Washington) the Columbia Plateau basalts are comprised
of over 200 distinct flows each of which has distinct characteristics. Each
individual flow in turn varies from bottom to top because as the flow
cooled, entrapped gases rose toward the surface leaving the upper portions
of each flow more vesicular (full of small voids) than the rest. Often the
bottom portion of a flow is of a punkier nature due to the fact that many
years accumulation of sediment, debris, vegetable matter ......and more
importantly standing water, was often present when the new flow "washed"
over the previous ones. Where a flow encountered  water it cooled very
quickly and often formed areas of yellowish plagonite that is punky and
often contains bits of glassy obsidian-like material and common opal.

My point here is that the structure of basalt is not constant. And even the
finest grained basalt will not accept a deep glass-like polish. As a
long-time gemcutter I've used every trick in the book to try to get a
perfect polish on carvings shaped from the blackest, finest grained material
available, and always come up short. My advice is to use the resin pads on
your wet-polisher and take it as far as you can.

Around here columns and boulders are often polished on certain edges and/or
faces leaving the oxidized weathered surfaces as a contrasting element.
Though not glassy, the worked surfaces look (AND FEEL) very nice.

Will
Glyptic Concepts