Two rock tumbler questions

Factual Questions
1

I enjoy collecting rocks and was wondering if you could use a rock tumbler to shine and smooth any stone you find, or is it only specific stones that will work. I am also curious if there is a way to make your own rock tumbler and what would you need to do this.

2

You migh smooth most types but not all will shine. For example a limestone will probably round down but only any shell fragments would ever shine in it.

The length of time required might also vary greatly.

I’d imagine most hobby stores will sell a bag of semi-precious “gems” to tumble. Other than that, just play and experiment. It’s one of the reasons I became a geologist. Have fun!

3

What lieu said.

For the second question, set yourself up any type of rotating drum, throw in your samples, some water, and some coarse grit at least as hard as your rocks: quartz sand will do for most common samples; silica-carbide grit is harder and will work faster, but is more expensive. Let 'er rip–you are essentially just simulating erosional processes in a laboratory, if you wanna get all scientific about it.

4

Well I have mostly quartz type stones of various colours. I think if I manually tumbled these rocks it would take a long time with me ticking off all my neighbours. So maybe I can get something to polish by hand. Any ideas?

5

All you need to get a good (relatively quiet) polish on quartz or other minerals or rocks is a sturdy glass plate, silica-carbide grit (get a coarse-grain for large samples), water, and lots and lots of time and elbow grease.

6

I remember that in HANDBOOK OF HOMEMADE POWER there was a guy who built a waterwheel on his property but didn’t quite know what to use it for. So he attached an old steel boiler tank to the shaft, filled it with hundreds of pounds of interesting rocks, and had the world’s largest tumbler.

7
      • To hand-polish stone, there are diamond tools used for sculpting and jewelry-making. Montoya and The Compleat Sculptor are two companies; last time I looked diamond-sandpaper pads 2 x 4 inches were about $35 apiece, available in different grits.
        ~
        The grab-bags that hobby stores sell are your best bet to get something that looks nice, without actually ordering rocks yourself from a jewelry or stone supplier. To polish well, the whole rock has to be hard, and it has to be an even hardness-- it can have different colors through it, but they all have to be the same hardness, and (in most places on earth) most ordinary rocks you find fail on this count. If you put them into a rock tumbler, when it’s done you end up with some fine sand (the softer parts) and some small chips (the harder parts).