OK. It isn't used in the reaction, but rather in the building. Will this work?
[BUILD_ITEM:1::TOOL:ITEM_TOOL_LARGE_POT:NONE:NONE][REACTION_CLASS:CERAMIC][EMPTY][NOT_CONTAIN_BARREL_ITEM][DOES_NOT_ABSORB][CAN_USE_ARTIFACT]
Edit: So, I went ahead and started to test it only some of the stuff isn't available at embark. Upon this reaction finishing, my game is now crashing. I think I messed up the product line but I'm not sure what it should be changed to. Below is the relevant info.
[INORGANIC:BAUXITE_POWDER]
[USE_MATERIAL_TEMPLATE:STONE_TEMPLATE]
[STATE_NAME_ADJ:ALL:bauxite powder]
[DISPLAY_COLOR:4:7:0][TILE:34]
[SOLID_DENSITY:1281]
[IS_STONE]
[REACTION:MAKE_BAUXITE_POWDER]
[NAME:make bauxite powder]
[BUILDING:QUERN:NONE]
[BUILDING:MILLSTONE:NONE]
[REAGENT:A:1:BOULDER:NO_SUBTYPE:INORGANIC:BAUXITE]
[REAGENT:B:1:BOX:NONE:NONE:NONE][EMPTY][BAG][PRESERVE_REAGENT]
[PRODUCT:100:1:NO_SUBTYPE:INORGANIC:BAUXITE_POWDER][PRODUCT_DIMENSION:150][PRODUCT_TO_CONTAINER:B]
[SKILL:MILLING]
Note you don't need to create a new type of stone to make a powder, just use this for your reation, cutting out the middle material, Also noticed your missing something from your reaction :/
[REACTION:MAKE_BAUXITE_POWDER]
[NAME:make bauxite powder]
[BUILDING:QUERN:NONE]
[BUILDING:MILLSTONE:NONE]
[REAGENT:A:1:BOULDER:NO_SUBTYPE:INORGANIC:BAUXITE]
[REAGENT:B:1:BOX:NONE:NONE:NONE][EMPTY][BAG][PRESERVE_REAGENT]
[PRODUCT:100:1:POWDER_MISC:NO_SUBTYPE:INORGANIC:BAUXITE][PRODUCT_DIMENSION:150][PRODUCT_TO_CONTAINER:B]
[SKILL:MILLING]
SO with this modified reaction theres no need to add [BAUXITE_POWER] as it will make powder from [BAUXITE] also fixed the [PRODUCT:...] you forgot the main type
[PRODUCT:(chance 1 - 100):(amount made):(main type):(subtype):(material catagory):(material)]
also your build item as a extra ':' after the 1. But I have no idea how get your buildmat to be that spacific, if the REACTION_CLASS works for the buildmat let me know