This was interesting. Found a flat rock in my yard and went to testing. I started low and fast and moved up to high and fast. Next, I need to find another rock and try high and slow. I don’t think the laser is actually engraving, I think it burned the rock. Is this true? The trial and error with this piece has been much of the fun.
Not burned in the conventional sense, its similar to what is happening if you were to laser glass or tile.
Kewl! (You need to laser “Put me Down” on the next one. )
I haven’t tried glass yet.
Or “Why are you looking here?” and then put it in an obvious place that someone might pick it up and turn it over.
…and engrave a key on the back side.
It will depend on the kind of rock. I think some might actually burn (e.g., undergo a rapid redox reaction with oxygen from the atmosphere) but I think most minerals are more likely to undergo thermal decomposition (e.g., calcium carbonate will decompose into calcium oxide and carbon dioxide) than to actually combust.
Thanks for this explanation.
Or “Hard Place” with an arrow pointing down.