In May, the LaFarge Quarry in Dundas will be open for a field trip to collectors associated with local gem and mineral clubs. I plan on attending this rock hounding opportunity, but Reiner has been good enough to provide me with some samples beforehand so that I can test certain minerals found at this location for their use as pigments.
One rock commonly found in this quarry is celestite. Celestite is oftentimes a pale blue (hence the name; it’s celestial) but if pure, as in this sample, it is white. Celestite is naturally occurring strontium sulfate. In reading a bit more about this mineral I was surprised to read that it has been lately identified as a pigment in 22 Greek steles in the Louvre. Commonly, the pigment made from this mineral is called strontium white.
In powdering the celestite it produced a good opaque white and it doesn’t seem to be affected by heat (at least at the temperature levels I’m subjecting it to). I’ll be curious to see what it’s brushing properties are like once I mix it with a binder.