Archae,
I appreciate the dialog.

Slide 21 shows more Magnesium 3.3-9.1% in the Lauer sample, vs. 0-.89% in the Tura Sample and the EA-491.

[en.wikipedia.org]
Asbestos("Mg3(Si2O5)(OH)4") has a Mg-Silicate bond... and is used in cement. The Calcium would come from the lime.

Compare: Kaolin Clay Al2(Si2O5)(OH)4 vs. Asbestos - Mg3(Si2O5)(OH)4

[www.neverpaintagain.co.uk]
"Confusingly, the Modern Greek word asbestos means quicklime."