We frequently tumble sterling and turquoise pieces in our steel
shot tumbler with a mild burnishing solution and don't have any
trouble with the stones. Good luck!
i can think of two types of turqoise where this would apply. Very
high grade, such as is sometimes called "Persian", can have high
levels of silica within it, raising the hardness enough so the shot
won't hurt it. And stabilized turqoise, which is impregnated with
plastic resins, could be tough enough to withstand it.
But untreated turqoise in qualities normally seen, would be risky.
But this would also depend on the tumbler, it's speed, how smooth
the shot is, and the nature of the burnishing solution. Some tumblers
are slower and more gentle than others, and if the shot is well worn
and fully smoothed out, especially if the mix doesn't have the
sharper needle shapes. In those cases, it could be possible that your
turqoise or other fragile or soft stones might do better than is
common seen, and if it works for you, then great. But many tumblers
and users thereof, may not be that lucky. Try it and see with a
sample of your material, and you'll have an idea. However, be aware
that this is probably pushing the limits of safety with a tumbler and
steel shot. The process can vary between gently massaging the
surfaces to make them relaxed and happy and ready for soft music, and
hammering the surfaces with miniature sledge hammers, depending on
the equipment and how it's used. But steel shot or other media
tumbling certainly could be tailored to work. After all, you can use
rotary or vibratory lapidary tumblers, with the right mix of
media/abrasives/polishing compounds to polish virtually any stone,
including turqoise, opals, or even amber. It can just take some
experience and experimenting to get the process to work without
damaging the stones.