Some framboid and colloform textures of pyrite in seafloor hydrothermal deposits actually are fibroradial spherulites of pyrite when viewed in partially polarized reflected light. “Colloform bands” in these pyrites are ring-cracks. This disequilibrium texture reflects rapid crystallization with undercooling caused by mixing between hot vent fluid and cold ambient seawater. In principle, different morphologies of spherulitic pyrite may indicate different degrees of mixing between vent fluid and seawater.