What's the plural form of ceylanite? Here's the word you're looking for.
Answer
The noun ceylanite can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be ceylanite.
However, in more specific contexts, the plural form can also be ceylanites e.g. in reference to various types of ceylanites
or a collection of ceylanites.