Produce a sentence which has a cefr level of "c1" and keywords: metals, fact, end, seventeenth, century.
In fact, by the end of the seventeenth century, chymists had also discovered zinc, bismuth, and possibly cobalt; but these were not grouped with the classical seven metals, and were sometimes called "bastard metals" because they did not fully share the characteristic properties of shine and malleability with the others.