岩石
がんせき · ganseki · JLPT N1 · noun
rock
🪨 岩 (rock) + 石 (stone): 'rock' stacks on 'stone' - a rock is just a big stone
岩 is the cliff-and-boulder character for large rock masses; 石 is the everyday word for stone. Together 岩石 names rock as a material. Say gan-se-ki, the first part sounds like 'gun' in 'gun-say-key'.