Stone: 石 (2)
石 means stone and usually sits on the left as いしへん. It fits 碑 (stone monument), 礁 (rock reef), 硫 (sulfur mineral), and 硝 (saltpeter); 磁 (magnet or porcelain) and 碩 (eminent) show that the association can be material or historical, not a literal stone in every meaning.
磁, 碑, and 碩 each have 14 strokes. Keep the left-side 石 compact so the right component has room.