Another Herkimer question

Ok, wow you guys are great I spent the morning reading up on
herkimer diamonds… but i have one question left.

One site claims herks are a hardness of 7 mohs, but because they’re
quartz does this mean they cannot be cast in place? I’m doing a
bronze/silver sculpture I wanted to incorporate some herks into, but
the water content of most quartz prevents this. So anyone know if you
can cast with a herk?

Thanks again,