An obscure spelljammer setting question

[FoxWander]

This had been driving me crazy. I seem to recall there was a mention in one of the setting books that named the material crystal spheres are made of. Does anyone else remember reading this and happen to recall that name? Or what book it was in? Any clues at all would be helpful. Thanks.

 

[Dioltach]

The easy solution -- a quick search on the Crystal sphere - Spelljammer Wiki -- gives an "unbreakable dark ceramic material".

 

[Silverblade The Ench]

Zodars are also made of it, but can't recall if it is ever named?
try asking on "The Piazza" spelljammer forums? they'd know

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