The Agate Pestle and Mortar Set is recommended for grinding very hard samples into powders. Agate is much harder than porcelain and limits the number of impurities introduced into the sample during grinding.
This set ships with the General Purpose IR Sampling Kits (51007739/L1365312) and the Liquid and Mull IR Sampling Kit (51008709/L1365311). With this part number, it can be ordered as a replacement or spare set.