Ultimate rotary polish comparison test?

A was predicted. Best shine ever on this for me.

Ashley, it was 2-3 years ago on eBay listed as Ohio Flint Ridge chert or flint. Also can show up as Nether's farm flint or chert.

It fractures super easily, and maybe half or more sort of fell apart. But, it's extremely beautiful and I'm glad I tumbled it. Found out spending a lot of time in 220 helped, rather than trying to get in perfect shape in coarse grind before going to 220.

Bob
I agree, chert is one of my favorites. An underdog for sure! I bought a few pounds of flint ridge flint from Kelly on here. It will go in the rotary next after some Quartz I have in. Really looking forward to seeing how it turns out.

A was predicted. This material drives me crazy because of those frequent porous area. But still T produced the best shine I've ever done. Opticon helps, but doesn't solve the porous problem. It's only for small fractures, not holes unless the holes are very tiny.

Bob,

Quick! - we need to corner the market in stannous oxide! 
What an effort on your part - well done!

Bob
Thank you Bob for all your hard work and your sharing with us! I enjoy waiting for you to show us more and to learn from your efforts! When you reference the “literature” recommending certain polish for certain rocks, what is the literature you speak of? A certain book? Numerous books? Books and websites?

I am processing a lot of this beautiful material after two collecting trips to Cerro Pedernal. I like it, but it's kind of weird stuff. When sawing off bad parts, of which there are many, there is a lot of fine chipping around the blade cuts as if this material is not strong and kind of brittle. Yet, when dropped, a piece rarely breaks which doesn't seem to fit a brittle material. I've never seen a conchoidal fracture in a single piece--which is extremely odd to me since this was a very important lithic material for tools made by original peoples according to several archeological papers. The combination of all those characteristics makes this material unique to me and kind of puzzling.  I don't have a way to test for Moh's hardness, but I suspect this is slightly softer than the 6.5-7.0 of non-specialized chalcedonies.  This is based upon its feel in my hands in the saw and how it reacts to coarse grind.  A is predicted for all non-specialized chalcedonies, but nothing was found in literature for this one.

I'm going to predict that not too many people in the forum are familiar with this material.  Never have I seen it listed for sale.  It's rather common and easy to find in it source location.  One of the things that makes it appealing in my opinion are translucent and transparent areas in some pieces that occur in kind of an unpredictable way.  For example, that dark piece on the left has regions that are opaque, some that are translucent, and some that are transparent--all in the same rock.  That's why in some photos the dark color sort of looks like it's within the rock.  Yet I have pieces that look at first almost just like that one, but the dark part is all the way to the surface and the entire rock is opaque or nearly so.

The T shine seems perfect. A was predicted from literature.

A few people have asked me me about why didn't I include zinc oxide and titanium oxide.

The reason I didn't include tit, tripoli, red rouge, and pumice is because my reading gave me the impression they were specialty polishes to use only for very soft materials that are rarely used in rotary tumbling.

The reason I didn't include boron carbide, boron nitride, and diamond is because my reading gave me the impression they were specialty polishes to use only for very hard materials that are rarely used in rotary tumbling.

I also didn't include M-5, but I can't remember why.

As to zinc, I don't think I had ever heard of it, but recently someone told me that is the polish that ships with Thumler's tumblers. Is it a widely used polish such that it being missing from this comparison is an oversight I should not have made?