Description of the Most Principal Mineral Ores

a few assay shards or crucibles, and assay in them a strictly hard-to-melt Erzt ore, so you will see whether the material will hold, be good, or be durable. Some also mix into it chalk stone, or subtle red talc and mica, in those places where there is much of the same; however, experience will show what will be most useful for this. Some take for this, broken shards of pottery or old crucibles, pounded small and sifted through a small sieve, under the clay, as much as they can barely work into the clay before it becomes brittle. Such crucibles and shards made from it hold well, but when Kißlingstein quartz/flint is used under it as reported above, it binds together in the fire, and the greater the heat, the firmer it binds, and the assay shards made from it press themselves out of the lining quite nicely.

On the lining or forms in which the assay shards are struck.

When now the material or clay has been prepared, then you must have forms or linings in which you can strike the assay shards and crucibles. These same forms are best made of brass; but whoever cannot have such, let them be turned from pear wood in such a way that one can push an iron ring onto it that fits snugly, so that the form or the lining, in the long run because of much use, does not split or break. Then grease the inside of the form with lard so that it becomes greasy, and put into it a ball of your prepared material, as much as you think is enough, and grease also the upper part of the lining, which one calls the Münich monk, likely referring to the male or plug part of the mold, and strike then such upper part with a wooden mallet into the form, so the shard is formed. As the lining is prepared, press it out with your fingers. Only have care that the clay is not entirely too moist, otherwise the assay shards would not let themselves be pressed out completely. Some lay the lining, together with the shard, on a sharp heat, then the shards go out soon and quite completely; that is surely a correct way to make small assay crucibles, so that one brings them all out completely, but with the assay shards, it will go slowly.

Making muffles from clay over a small wooden block.

For making the muffles, you must have cut small blocks, according to the form and size as the muffles should be. The best way is to smear them with the lard and make first a lump of clay so large that you can cut a thin sheet from it with a small copper wire; that, spread over your small block, and cut also from such a cut sheet, a semi-round little piece,