chalk/lime/hair plaster

I'm wanting to try my hand at plastering over fixall (short-straw, fine cob) with chalk, lime, and hair (being used on restoration projects in the UK) and I would make the mixture myself, but I can't seem to find any supplier who sells big ole' bags of chalk (calcium carbonate) -- I mean like wholesale, 80-100 lbs.  There's plenty in art supply, food industry, and pharmaceutical suppliers with tiny little amounts of way-too-fine quality versions, hugely expensive.  Then, I suppose there's just trying to visit every school in eastern Washington State for their old supplies of chalk that no one is using anymore and crushing it myself (good re-use, pretty time intensive, and likely not much out there).  Any ideas?

I'd suggest looking at other types of calcium carbonate. It's available in the form of limestone, shells, bone, and in processed forms like quicklime or slaked lime.

If you're determined to go with chalk, look for raw chalk, not the refined stuff used in drawing or food industries. I don't know if there are any chalk deposits near you, but if so, you might be able to talk to the quarry owner or landowner directly and see if they'd sell you some.

Thanks, Ellandra!  I was looking for bulk calcium carbonate of all kinds.
Lime, as it is processed, is a different ingredient for the recipe - serves as the cement component.
I think the Angliamix is using raw, crushed limestone chalk for the aggregate.
I'll keep searching -- you're right that I have to search out chalk mines and either get it from them or follow the trail from there.
I appreciate the response.