Modifiers matching rock:

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

Simple categories matching harder:

• food,
• medium,
• material,
• glass,
• stone,
• boot,
• substrate,
• stuff,
• particle,
• surface,
• metal,
• feldspar,
• drug,
• crystal,
• filler,
• powder,
• tissue,
• substance,
• mineral,
• gemstone,
• genre,
• rock,
• object,
• aggregate,
• alloy,
• ground,
• currency,
• formation,
• wood,
• agent,
• cheese,
• abrasive,
• part,
• pin,
• ingredient,
• sport,
• work,
• assets,
• thing,
• polymer,
• resin,
• structure,
• fabric,
• stimulant,
• sediment,
• deposit,
• layer,
• narcotic,
• music,