The rubrics in force do not REQUIRE metal, but do require a chalice to be all of the following:
- Non-porous material
- durable material (not gonna rot)
- non-fragile material (not easily broken)
- noble material
Those rubrics have been in force the entire time. Hence the reprobation on glass chalices; it violates #3.
Most wood violates #4, much wood violates #1 and #2, and some wood violates #3.
Clay violates 1,3, and 4.
RS makes it clear that #4 isn’t “artistic merit” alone but actual use of noble materials. Materials with intrinsic value.
for example:
A priest-theologian of my acquaintance obtained his bishop’s permission to continue using his Ebony chalice and patton after RS. It’s precious, as it’s real ebony wood, and that’s rare. It’s been coated with a non-porous non-alcohol-soluble resin, making it both non-porous and more durable. Ebony is actually rather durable as a wood by itself, and not terribly fragile. (I’ve seen it survive a fall from the creedence table). From a distance, this set looks like glass.
But I’ve also seen metal vessels damaged significantly by short drops. A silver with gold-plating ciborium was dropped a few feet, and cracked. Perhaps a bad batch of silver, not alloyed properly.
