Kang prepared robot duplicates to replace the slain counterparts to rule the empires of every Kang in existence. At the same time, Kang re-took his 40th-century base via his Growing Man. After the rest of the counterparts were eliminated, the prime Kang slew the rest of the Council.
Stoneware is a rather broad term for pottery or other ceramics fired at a relatively high temperature. A modern technical definition is a vitreous or semi-vitreous ceramic made primarily from stoneware clay or non-refractory fire clay.
Glass is made of silicon. The only mineral made up exclusively by silicon is quartz, which is also the main mineral in common sand. So the answer is quartz, but you're not wrong thinking sand, only sand is not a mineral.