Modifiers matching rock:

• sedimentary,
• bituminous,
• hard,
• geologic,
• weaker,
• metamorphic,
• alkaline,
• widespread,
• basic,
• dense,
• igneous,
• competent,
• volcanic,
• coarse,
• consolidated,
• difficult,
• porous,
• suitable,
• enough,
• soft,
• intrusive,
• crystalline,
• dry,
• impermeable,
• deleterious,
• massive,
• pulverized,
• reactive,
• smooth,
• softer,
• crustal,
• weak,
• flinty,
• russian,
• crushed,
• polycrystalline,
• polyphase,
• covered,
• polished,
• ordinary,
• artificial,
• siliceous,
• clastic,
• elastic,
• simple,
• related,
• virgin,
• harder,
• homogeneous,
• planetary,
• impenetrable,
• molten,
• tough,
• dark,
• barren,
• red,
• dated,
• marine,
• ingenious,
• refractive,
• rough,
• typical,
• azonic,
• granular,
• refractory,
• precious,
• impervious,
• noble,
• ornamental,
• rigid,
• salt,
• egyptian,
• underlying,
• tight,
• coloured,
• acidic,
• heated,
• unstable,
• combustible,
• acid,
• intermediate,
• stable,
• unconsolidated,
• angular,
• flying,
• metallic,
• heavy,
• aluminous,
• colorful,
• calcareous,
• geological,
• friable,
• firm,
• decorative,
• magnetic,
• natural,
• available,
• normal,
• nonporous,
• strong,
• permeable,
• indigenous,
• chemical,
• vitreous,
• anisotropic,
• hot,
• sedentary,
• modern,
• fragmented,
• resistant,
• subsurface,
• conductive,
• flat,
• new,
• traditional,
• original,
• sharp,
• small,
• british,
• good,
• useful,
• powdered,
• durable,
• inappropriate,
• smaller,
• abrasive,
• crumbly,
• heterogeneous,
• exotic,
• colored,
• inert,
• compact,
• large,
• opaque,
• native,
• plutonic,
• brittle,
• surrounding,
• light,
• insoluble,
• carbonaceous,
• ductile,
• organic,
• visible,
• soluble,
• eruptive,
• extrusive,
• non-porous,
• common,
• primary,
• fine,
• rich,
• unusual,
• loose,
• looking,
• spherical,
• lighter,
• glassy,
• white,
• terrestrial,
• size,
• free,
• fragile,
• frozen,
• reflective,
• heavier,
• argillaceous,
• sticky,
• lightweight,
• older,
• local,
• abundant,
• hardest,
• korean,
• base,
• uniform,
• stronger,
• extraterrestrial,
• industrial,
• solid,
• textured,
• isolated,

Simple categories matching combustible:

• fumes,
• gas,
• mixture,
• waste,
• vehicle,
• garbage,
• container,
• substance,
• chemical,
• particle,
• hydrocarbon,
• sheet,
• item,
• compound,
• metal,
• adhesive,
• debris,
• fabric,
• article,
• dust,
• scrap,
• fuel,
• fraction,
• powder,
• solid,
• filament,
• matter,
• oil,
• component,
• structure,
• product,
• wall,
• fluid,
• decoration,
• material,
• liquid,
• contaminant,
• foil,
• volatile,
• solvent,
• space,
• residue,
• object,
• surface,
• mineral,
• wax,
• nature,
• fiber,
• deposit,
• rock,
• construction,
• equipment,
• land,
• vegetation,