9 quartz glass products for use in the chemical industry, in the electrical industry, in the semiconductor industry and for laboratory purposes, namely cuvettes, inspection glasses, flasks, crucibles, dishes, beakers, frits, ground slides, trays, diffusion tubes, bells, epitaxy tubes, boats, catalyzer carriers; quartz glass products for optical equipment, namely lenses, prisms, plates, filters, mirrors, mirror carriers, optical guides; optical fibers