Modifiers matching rock:

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

Simple categories matching impenetrable:

• rock,
• layer,
• portion,
• surface,
• material,
• obstacle,
• member,
• vehicle,
• structure,
• obstruction,
• substrate,
• object,
• barrier,