I'm in SW Ohio and I just got into rock hounding. Where I'm at, we have a lot of granite, rose quartz, calcite, gypsum, flint, geodes, and many many fossils (brachipods and various corals). I am totally new to the whole process, but I went rock hunting in a creek bed and found some cool stuff. I'd ideally like to polish my finds and make some jewelry, but I'm a college student on a budget with limited access to stone working tools like rock saws. I'd like some advice and tips on how to make a limestone/dirt covered hunk of granite into something pretty and shiny, and how to best turn a nice piece of horn coral, quartz, and so on into a necklace or earring. So far I've been cleaning them with vinegar and a needle, and working with sandpaper of various grits, but it's slow work. I'm a bit apprehensive to get HCl or Oxalic acid, but mostly since I'm not much of a hardware person.
My dad has a cement churner that he's ok with me using, would that work too? I read that tumbling rocks takes a few weeks. But I'm not sure that's what I want if I want to remove thick layers of limestone in the nooks and crannies of a fossil, I'm trying to find good (chemical?) ways to spot clean without damaging the mineral itself.
Aw no, this is my first time on /diy/, many apologies.
The best polishing surface for rocks is other rocks. You can rub them together by hand (slooooow), or use a rock tumbler as others said. Google it, they are very common. Commercial tumblers tumblers and DIY designs are both very easy to find online.
If you want to remove the cortex, eg from cracks, try soaking in vinegar for a week, or scrubbing with a toothbrush and toothpaste. Should remove all the oxidation easily enough.
>My dad has a cement churner that he's ok with me using, would that work too?
Rock tumbling is to give a polished appearance to rocks. It's basically sanding the rocks. A cement mixer is not made to run 24/7 for weeks on end. Plus it is open and will allow the water to evaporate.
If you want to remove limestone, acid is your friend. Vinegar will work. Stronger acids will work more quickly but also do more damage to the mineral.