The DFC Assay Crucibles feature the standard clay blend and the Colorado
Blend of clay crucible. Both are for working temperatures up to 2,000o F
(1,800o C).

The standard clay crucible is designed to give suitable use under
standard operating conditions. The Colorado Blend clay crucible has a
higher thermal shock rating, and will generally have a longer life in
assaying applications. The clay from DFC crucibles comes from their own
clay mining operations, and a high degree of quality control is achieved
in processing clays for crucible manufacture.

Currently, 40 gram and 30 gram are the primary size crucibles used for fire assaying. All assay crucibles will give good service at temperatures up to 2,000 degrees F (1,093 degrees C).