I've been keeping the reaction on repeat for the last few in game years with no gems created. Suggestions stated that I should replace :STONE: with :ROUGH: so I will try that. I also like the idea of creating a primary reaction that will create a geode, which can then be cracked.
[PRODUCT:1:1:ROUGH:CRYSTAL_ROCK] will not work, but [PRODUCT:1:1:ROUGH:NO_SUBTYPE:STONE:CRYSTAL_ROCK] will.
My own testing suggests that, at least with 40d16, it is in fact a roll of the dice for these reactions,
not a cumulative build-up (leading to a sudden springing forth of 10 different gems after feeding in exactly 100 rocks, for instance)*. With a list of eight different possible product gems, each at the 1/100 level, and using the manager to run the "crack geode" reaction 100 times, some gems came quickly and were duplicated before 100 were finished, and some were not rolled at all within the 100. (All reactions done at the same smelter).
* Perhaps with ores, like tetrahedrite, it is a build-up, while with reactions it is a random chance?
Potential products listed in-game for the "Crack Geode" reaction:
Rough rock crystals (1%)
Rough ametheysts (1%)
Rough aventurine (1%)
Rough smoky quartz (1%)
Rough rose quartz (1%)
Rough citrines (1%)
Rough rhodolites (1%)
Rough peridots (1%)
Yield from 100 "crack geode" reactions:
Rough rock crystals: 1
Rough citrines: 1
Rough adventurine: 2
Rough smoky quartz: 2
Rough rhodolites: 1
Rough ametheysts: 2
As for the fact that all stones can be used, is it possible to use the [IGNEOUS_INTRUSIVE],[IGNEOUS_EXTRUSIVE], or [METAMORPHIC] tokens to specify stones used in a reaction? Or can I only use the stone-specific tokens?
I haven't tried this, but what Retro42 said will work quite well: find every rock type you want to have a geode (for instance, go to matgloss_stone_layer and check every stone that isn't flux* or obsidian), and add [REACTION_CLASS:GEODESTONE] to the end of their entries.
Then, in your reaction_geode, have your reagent be:
[REAGENT:1:REACTION_CLASS:GEODESTONE]
*Or not. You may have more flux layer stone than you know what to do with, and limestone, for instance, is a common enough place to find geodes.