Yup! Turtle back, I'm not sure if it one word or two, though.
Bob

Brazilian Agate that is a smaller one for me at 2-1/4" tall.
Bob

Around the house and garage I use Nitrile gloves from Costco. 2 boxes with 100 pair in each box for less than $20. They are safer than latex because if they snag on something they will tear. Latex gloves snag and stretch and pull your hand into any rotating machinery. Mostly I use dops to give me better grip and control of the cab especially when polishing. When I'm sanding I sometimes use my finger on the underside to tell me that I'm not rocking the cab too far, but only on the finer grit belts. I do often grind/sand my left index nail and a little skin at times. Its just the price to pay for having fun doing lapidary.
Bob 

Green moss possibly Horse Canyon or from Oregon. The green Moss from India is generally more translucent.
Bob

I just use the standard grinding and sanding wheels. I do most of my work on an 8" wheel machine. You just turn the preform so the girdle is pointing at the wheel at the place you want the concave to be and grind in as far as you want. Then you turn the preform flat and continue grinding the rest of the girdle. As you grind the dome, when you get to the concave area  turn the  girdle towards the wheel and rock the preform inwards so the grinding will make that area concave. I generally work the concave inward about half way to the center but the rest of the dome grinding will continue all the way to the center. The sanding activity is done the same as the grinding. The curvature of the concave will match the diameter of your wheels. If you want a deeper concave you will have to go to a machine with smaller wheels. I have a home made carpet covered polishing wheel that I use almost exclusively for my polishing. When I made it I curved the outer front edge so that it would reach into the concave areas on the cab. This is very difficult to polish on a flat wheel.
Here is an example of a Montana Agate cab that I did with a concave side on it. The cab is about 3" tall. I have made some cabs with all four sides concave so it has a star shape to it . I don't have a photo of them but I will try to get some photos to show as an example, perhaps today.
Bob

Plant more rock seeds and before you know it up pops more rockhounds!
Glad you had a great show!
Bob

I always put a small bevel on the back edge on my cabs for all of the above reasons. It just gives a finished look and feel to the cab. Depending on the size of the cab (I do make cabs up to 6" across) the bevel width can be from 1/32" to 1/16" across. I hold the cab at a 45 degree angle and sand the bevel on a worn 220 grit S/C belt with a lot of water on the belt to keep the edge cool. I follow this with a worn 400 grit S/C and then to polish. It takes a few minutes but the time is well spent.
Bob

This is today's cab. It is Brazilian Agate with a small druzy pocket. It is 4" tall and is destined to go into our display case that we take to regional gem and Mineral shows.
Bob

Does anyone have any experience with rebuilding Poly Arbors?
Our club has many of these in the shop and we are having to replace the bearings in one and the bearing info doesn't come up on any bearing supplier's books.
Part no.  RAO12 CRS-2
Mfg. Koyo
Bob

I cut these at about 3/16" thick so they can show any transparency/translucency that may be in the material. This is the same thickness that I cut the large slabs, too. It is a bit more work to get a dome on my 4" to 6" wide cabs but the beautiful patterns are worth it. When I'm making cats eye obsidian cabs from the Davis Creek rainbow material I cut them almost 1/2" thick so the cab will have the black density to show the cats eye effect.  I am also hooked on obsidian and have been for 40+ years.
Bob

Recently when I was digging through some Glass Buttes smaller pieces that I collected with my dad about 30 years ago I came across this one. It doesn't show much from the outside but I cut it just to see what it had inside. This photo shows the outside surface. There is no indication of any translucency in the black areas. It is about 5" across.

This photo shows the other side after I cut about 5 slabs from it. This side is shown polished and the black areas just look black!

This photo shows the last slab from the rough piece shown in the previous photo. It is polished on both sides. Striking, huh?
 
This photo is one side of the polished second slab from the rough. It is about 3" across.

This is the other side of the polished second cab from the rough.

I was surprised with what was inside such a ordinary piece of this material. This came from the digging area on the right side of the road coming off the highway past the cattle guard about halfway to the pond area.
I'm going to explore the innards of some of the other ordinary pieces that I have from that first digging many years ago.
Bob 

I only use Handi Flux (borax) and it works great for me.
Bob

The colors are like Paul Bunyon material but the pattern isn't.
Bob

Obviously a space ship landing site!
Bob

You can get felt sheets at McMaster Carr and use a gasket punch to cut out the circles for polishing wheels.
Bob