While I don't usually go for knick-knacks, I thought this one was blog-worthy! It starts about 1988 when I discovered these pretty black rocks with green inclusions on a deserted Mexican beach literally in the middle-of-nowhere. There was a huge outcropping of them in this little cove and I loaded up the van likely with close to 50kg of them. I swapped the biggest pieces to a local rock shop in exchange for some diamond sawing of some glass boules that the astronomy club had - cut into manageable blanks, they were much more useful than 30kg chunks!
Anyway, about that time, the thing to do with pretty rocks was to make a sphere out of it and polish it. I picked out a nice one and intended to make about a 8cm sphere - even used the diamond generator I had access to at the time (Optical Sciences Center) to rough-in the shape. And there the project languished for about 25 years...
Fast forward to a couple weeks ago. One of the projects I can't tell you about has me making little glass spheres of various sizes. Shown at left, there are currently 3 diameters from 1" to 2.5". These are in various stages of completion, but will eventually have a fine-ground finish. The link to our story today is that I've become pretty proficient at making these. You start with a raw chunk and use a tile saw to make it approximately spherical a little oversize. Then you get out or borrow the "Sphere maker" shown at right. It uses 2 counter-rotating cups of appropriate diameter, and slight angle between them with abrasive powder the operator adds to grind off the high spots, resulting in a smooth sphere. Grind down far enough to remove any irregularities, work through finer and finer abrasives, and eventually you end up with a polished surface.
So finally, after waiting about 25 years to finish smoothing out my partially finished pretty rock, I re-did the finest stages of grit and polished it up in no-time! I had even saved a corner off the original rock, ground a concave into it and use it now with a few spots of felt to make a holder for it. Final product is shown at left. As you can see, the raw rock is nothing much to look at, but when polished, or wet on a distant Mexican beach, it does indeed look impressive.
I've since found out that a popular name for the rock is "nebula stone" - so named for the green inclusions resembling telescopic views of green planetary nebula in the night sky. The other day I Googled "nebula stone" and found the name is copyrighted! You can follow the Google links yourself, or go to the Nebulastone company. Of course, they have all sorts of metaphysical effects attributed to these, and are charging outrageous fees - from something over $1/gm for tiny pieces to up to $4/gm for large polished pieces. I should rent a dump truck and go looking for that beach again!