[collingreen]

Sand is a bunch of tiny bits of a variety of things - we usually don't say micro-silica, micro-quartz, micro-etc and just bundle it together and describe the group as sand (unless explicitly trying to talk about an individual piece).

[more-nitor]

...and wouldn't that actually be problematic in health-related research?

I mean, it seems like saying copper/iron/titanium/lead are all "metal"