Basalt Crushing Technique 2

Skillet and wood platform
Skillet and wood platform

This is the second attempt to crush basalt gravel into usable particle sizes for the SPORE Pressure Experiment 1.

Once again, I’ll call it a failure. I learned a bit but in the end it just won’t for what I need it to do.

Cast iron skillet/ 4-pound hammer/ wood base


  • To make enough basalt particles of the correct sizes to start running the SPORE Pressure Experiment 1.
    • 2000 microns (#10 sieve)
    • 63 microns (#230 sieve)


  • 0.5″-1″ basalt gravel
  • 10″ cast iron skillet
  • A lumber and plywood base
  • A small paint brush
  • A large chunk of abandoned concrete (used as an “anvil”)
  • 4-pound engineering hammer
  • Geology screen sieve set
  • Personal protective equipment (PPE) Gloves
  • Impact resistant goggles
  • Dust mask (not needed)
  • Ear plugs (not needed for this experiment but would definitely be necessary if I continued for much longer).


  • I had planned to nail all the lumber together to form a solid frame but I started with just laying the plywood on top of the lumber.
  • I placed the skillet on the plywood.
  • After 20 swings I poured the crushed basalt into the sieve.
  • After shaking the sieve stack I placed the larger pieces back into the skillet.
  • I transferred the contents from the #10 and #230 sieves into plastic baggies.
  • Repeat step 2.
  • I went outside and used the concrete block after a couple of unsatisfactory attempts with the wood block.


  • After only a few hits I noticed that the basalt was not breaking as easily as in the previous technique. I’m pretty sure the wood platform was absorbing too much of the hammer’s energy. The basalt broke up relatively easily once I switched back to the concrete block.
  • Basalt loss was significantly increased once I switched to the concrete block however. Several large pieces flew out of the skillet and were not able to be recovered.
  • It was a lot easier to recover the fine crushed basalt from the skillet with the paint brush than from the tarp.
  • It didn’t take a lot of effort to start crushing basalt gravel, especially when I didn’t hold back (trying to reduce the amount of fragment loss).
  • The skillet showed no damage from this experiment. Of course, I only beat on it for less than 20 minutes total. Still, I half expected it to crack after a handful of solid hits.
  • Again, the hammer and sieves worked great. Solid purchases.
  • I had to temporarily suspend operations and move my gear to let a landscaping crew get by. They were nice about it.


  • I don’t see any reason (so far) why a Homesteader couldn’t use an hammer (made of Lunar iron) and a Lunar iron striking surface to break down mare basalt gravel. I haven’t tried it yet with an iron hammer but the tempered steel one I have works great. That will be for a future experiment. It’s not ideal or particularly efficient but it’s there if they need it.
  • The wood base didn’t work. I think it was absorbing too much of the hammer’s energy. The gravel wasn’t breaking nearly as easily as in Technique 1. Plus, our balcony is semi-enclosed and breaking rocks there was really loud. I don’t need angry neighbors. So I went back to the concrete block.
  • The basalt loss is unacceptable for this experiment but may not be for Homesteaders or a more advanced experiment.
    • An enclosure could be built that would contain flying rock fragments. The fragments can then be collected and crushed without worry about contamination.
    • I’m not sure how concerned Homesteaders will be if their crushed basalt is contaminated by whatever is on the floor. They could just sweep up the fragments, crush them down, and feed them to the next machine (whatever that is).
  • I’ve been thinking that the next step would be to purchase a ball mill. Ball mills are used extensively to grind rock into powder here on Earth. Then I got to thinking about Luna’s 1/6 gravity and how well a ball mill will work there. The balls need gravitational acceleration to get the energy needed to break up rock. A traditional ball mill might not be effective enough on Luna. I’ve got some thinking to do.
  • I’ve also started researching manual rock crushers. It seems the gold prospecting community likes this kind of stuff. I already found a couple of interesting ones. Definitely a step up from a hammer and skillet.


Not working very well
Not working very well
Crushing basalt in a skillet
Crushing basalt in a skillet

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