Klingenberg clay, which among other things is used in the pencil industry as a graphite additive, is still quarried today as it has been for hundreds of years (first documentary mention in 1567), albeit not in such great quantities as in the past.
Klingenberg clay, which is used as a graphite additive in the pencil industry, is still mined today, having been so for centuries (first documented mention in 1567), although not in such large quantities as before.