Peach sand used in limestone pointing

Here we have what was common in older stonework around Perth. This high clay sand mixed with slaked lime putty to produce an ochre coloured mix common in bagging and white washes of Rottnest etc.

I dare say all of it was burnt in a wood fire, then the rocks slaked but the burnt 'lime sand' with the associated clay mixed with the slaked lime and possibly some conch.