Mostly throwing in the towel after 6 yrs rotary quartzite!
Aug 20, 2020 10:57:44 GMT -5
Fossilman likes this
Post by Bob on Aug 20, 2020 10:57:44 GMT -5
I live in a part of the country where the alluvial outwash to the SW from the Rocky Mountain uplift has left a huge variety of quartzite. It's in many colors and some has pretty patterns caused by minerals that seeped in. There has usually been a few pieces of it in my tumbling batches. It takes forever to get the fractures out, as there are few pieces in the field w/o some fractures. But, with patience, this stuff just looks gorgeous going all the way through up to polish, then it' a gamble. Some pieces come out ok, some don't. Sometimes in the field we even find pieces w/o fractures that are pre-tumbled in a river.
An old timer tumbler told me it's a matter of whether the quartzite is "tight" or not. Tight ones have very few crevices between the recemented sand grains. Those often come out okay, he said. In 6 years of trying I've accumulated maybe 100 keeper polished pieces. Some are pink, some orange, some white, some brown, some almost black, some deep maroon, some gray and a few patterned. One of my largest tumbled rocks is a large piece of this, opaque but with pretty patterns that somehow come out with a nice shine--not perfect--but nice. However, the frustrating part is I probably tumbled 1,000 pieces to get those 100 keepers. Most had problems that became apparent coming out of 600 grit but a lot not until in polish.
So I have taken to sitting down with a 10x lens and looking at the surface coming out of 220 or 600 and getting rid of pieces for which those crevices are obvious and keeping the rest, thinking I've got it figured out and found the tight pieces. High hopes...
Well, I want to share what happened and why I'm really pissed off and have developed a strange dislike toward quartzite! It took a year or more to get a lot of what looked like high quality pieces ready for alum ox. My last 4-5 polish runs have been about 1/2 of these supposedly high quality quartzite pieces, together with misc. other stuff. Every single batch has been ruined by the quartzite. There has always been at least 1 and sometimes many more quartzite pieces that end up with banged up edges and mess up a lot of other rocks except for the hardest jaspers and agates. Now, by messed up, I don't mean ruined literally, as all can be repaired in just 1 or 2 runs back in 600 or 1,000.
Apparently, at least for me, what I'm concluding is that no matter how hard I try, it just isn't possible to predict which quartzite will come out good and which will go bad, even examining the surface with a 10x lens. It's just not worth it to me to continue this anymore as I'm so tired to having to reprep the rocks affected by the bad pieces for another polish run. I'm just going to keep what I was lucky enough to have done in last 6 years, and stop collecting it in the field (which is hard especially when the setting sun just lights up a pretty piece like a lantern). And for the pieces that I just can't part with, I'm going to do a special run in 1,200 or 1,500 SC and stop them there with a satiny finish like I do the gabbros, basalts, granites, gneisses, etc. In other words, I'm not even going to waste my time anymore testing a polish run.
Has anyone else experienced severe frustration like this with quartzite?
An old timer tumbler told me it's a matter of whether the quartzite is "tight" or not. Tight ones have very few crevices between the recemented sand grains. Those often come out okay, he said. In 6 years of trying I've accumulated maybe 100 keeper polished pieces. Some are pink, some orange, some white, some brown, some almost black, some deep maroon, some gray and a few patterned. One of my largest tumbled rocks is a large piece of this, opaque but with pretty patterns that somehow come out with a nice shine--not perfect--but nice. However, the frustrating part is I probably tumbled 1,000 pieces to get those 100 keepers. Most had problems that became apparent coming out of 600 grit but a lot not until in polish.
So I have taken to sitting down with a 10x lens and looking at the surface coming out of 220 or 600 and getting rid of pieces for which those crevices are obvious and keeping the rest, thinking I've got it figured out and found the tight pieces. High hopes...
Well, I want to share what happened and why I'm really pissed off and have developed a strange dislike toward quartzite! It took a year or more to get a lot of what looked like high quality pieces ready for alum ox. My last 4-5 polish runs have been about 1/2 of these supposedly high quality quartzite pieces, together with misc. other stuff. Every single batch has been ruined by the quartzite. There has always been at least 1 and sometimes many more quartzite pieces that end up with banged up edges and mess up a lot of other rocks except for the hardest jaspers and agates. Now, by messed up, I don't mean ruined literally, as all can be repaired in just 1 or 2 runs back in 600 or 1,000.
Apparently, at least for me, what I'm concluding is that no matter how hard I try, it just isn't possible to predict which quartzite will come out good and which will go bad, even examining the surface with a 10x lens. It's just not worth it to me to continue this anymore as I'm so tired to having to reprep the rocks affected by the bad pieces for another polish run. I'm just going to keep what I was lucky enough to have done in last 6 years, and stop collecting it in the field (which is hard especially when the setting sun just lights up a pretty piece like a lantern). And for the pieces that I just can't part with, I'm going to do a special run in 1,200 or 1,500 SC and stop them there with a satiny finish like I do the gabbros, basalts, granites, gneisses, etc. In other words, I'm not even going to waste my time anymore testing a polish run.
Has anyone else experienced severe frustration like this with quartzite?