Moonstone Gabbro and Labradorite (UV18 mixed batch pt.3)
Jun 9, 2018 11:05:53 GMT -5
jamesp, fernwood, and 1 more like this
Post by tkvancil on Jun 9, 2018 11:05:53 GMT -5
Finished my first batch of the year. It was a mixed batch of jaspers, agates, obsidian, feldspars, chert and gabbro. This particular mix yielded mixed results. All the Mohs 7 stuff fared well. Feldspars and gabbro turned out poor to good for the most part. The obsidian got scratched up so the shine was sub-par for what I usually get.
Part three of the mixed batch is the "problem children". Feldspars can be a challenge to tumble. The alternating layers that produce the chatoyance can be thin and fragile. They can also have layers at right angles so cleavage lines can undercut where the bonds are "softer".
Let's start with my Kryptonite, Labradorite. This would be my third attempt at this beautifully frustrating rock. For rough grind I use 220 in the rotary. Every time I've tried coarser grits undercutting becomes the norm. This third run was the same as the first two ... looking pretty good till polish ... then it goes to crap. I have become convinced the only way to get clean tumbles from this rock is to stabilize or dry polish, may have to try it.
Here is a shot of the whole bunch of Lab. It does have flash and the shine is good where the surface integrity is clean.
IMG_4588 by Ken Vancil, on Flickr
This shot shows what went wrong. All the white that looks like dry polish was not present after the AO500 vibe cycle. It's not dried polish although there may be a little in there. It is the edges of the layers that are fractured. When looked at under a 10x loupe broken jagged edges are clearly visible.
IMG_4592 by Ken Vancil, on Flickr
There were a few I'd call marginally acceptable, good flash and a lesser amount of damage.
IMG_4585 by Ken Vancil, on Flickr
This would be Indigo Gabbro, aka Mystic Merlinite. A muti-layered and multi-composition stone, granite like, when I first saw it I had little hope it would do well. Some damage at the edges of the layers like the Lab although not as severe. It's the metallic areas, silver and gold, that change color/shade when changing view. Often subtle, it's further diminished by the fact it is one part of the stone affected by damage in the polish. Came out better than expected, another stone that would benefit from stabilization I think. Some in the one and a half to two inch range.
IMG_4525 by Ken Vancil, on Flickr
Some smalls, half to three quarter inch.
IMG_4524 by Ken Vancil, on Flickr
A crop from the first group pic shows the bad and good.
IMG_4527 by Ken Vancil, on Flickr
More crops here flic.kr/s/aHsmjsKkJV
The Moonstone did the best out of all the "kids".
IMG_4531 by Ken Vancil, on Flickr
Only had a small amount of this type, came in Rock Shed's mix.
IMG_4537 by Ken Vancil, on Flickr
It's "fire" appears to be below the surface, more intense in person, hard to photograph.
IMG_4535 by Ken Vancil, on Flickr
IMG_4539 by Ken Vancil, on Flickr
Multi-colored came from the Gem Shop.
IMG_4551 by Ken Vancil, on Flickr
It's "fire" appears more on the surface, silver to blueish mostly. Also hard to photograph, three attempts.
IMG_4541 by Ken Vancil, on Flickr
IMG_4544 by Ken Vancil, on Flickr
IMG_4547 by Ken Vancil, on Flickr
Until next time ... Thanks for looking and keep on rollin' them stones.
Part three of the mixed batch is the "problem children". Feldspars can be a challenge to tumble. The alternating layers that produce the chatoyance can be thin and fragile. They can also have layers at right angles so cleavage lines can undercut where the bonds are "softer".
Let's start with my Kryptonite, Labradorite. This would be my third attempt at this beautifully frustrating rock. For rough grind I use 220 in the rotary. Every time I've tried coarser grits undercutting becomes the norm. This third run was the same as the first two ... looking pretty good till polish ... then it goes to crap. I have become convinced the only way to get clean tumbles from this rock is to stabilize or dry polish, may have to try it.
Here is a shot of the whole bunch of Lab. It does have flash and the shine is good where the surface integrity is clean.
IMG_4588 by Ken Vancil, on Flickr
This shot shows what went wrong. All the white that looks like dry polish was not present after the AO500 vibe cycle. It's not dried polish although there may be a little in there. It is the edges of the layers that are fractured. When looked at under a 10x loupe broken jagged edges are clearly visible.
IMG_4592 by Ken Vancil, on Flickr
There were a few I'd call marginally acceptable, good flash and a lesser amount of damage.
IMG_4585 by Ken Vancil, on Flickr
This would be Indigo Gabbro, aka Mystic Merlinite. A muti-layered and multi-composition stone, granite like, when I first saw it I had little hope it would do well. Some damage at the edges of the layers like the Lab although not as severe. It's the metallic areas, silver and gold, that change color/shade when changing view. Often subtle, it's further diminished by the fact it is one part of the stone affected by damage in the polish. Came out better than expected, another stone that would benefit from stabilization I think. Some in the one and a half to two inch range.
IMG_4525 by Ken Vancil, on Flickr
Some smalls, half to three quarter inch.
IMG_4524 by Ken Vancil, on Flickr
A crop from the first group pic shows the bad and good.
IMG_4527 by Ken Vancil, on Flickr
More crops here flic.kr/s/aHsmjsKkJV
The Moonstone did the best out of all the "kids".
IMG_4531 by Ken Vancil, on Flickr
Only had a small amount of this type, came in Rock Shed's mix.
IMG_4537 by Ken Vancil, on Flickr
It's "fire" appears to be below the surface, more intense in person, hard to photograph.
IMG_4535 by Ken Vancil, on Flickr
IMG_4539 by Ken Vancil, on Flickr
Multi-colored came from the Gem Shop.
IMG_4551 by Ken Vancil, on Flickr
It's "fire" appears more on the surface, silver to blueish mostly. Also hard to photograph, three attempts.
IMG_4541 by Ken Vancil, on Flickr
IMG_4544 by Ken Vancil, on Flickr
IMG_4547 by Ken Vancil, on Flickr
Until next time ... Thanks for looking and keep on rollin' them stones.