I’m not sure when Hill Brothers Chemical Company first started manufacturing Magnesite, however, it’s safe to say it’s been around California, Arizona, Nevada and other Western states for a long long time…it’s distinctive bull nose edges are a sure sign of what the deck has on it.

What I do know is that up until 1977, Magnesite was manufactured using Asbestos as an ingredient. Hill Brothers sold millions of square feet of the material as interior and exterior flooring. This 1999 article from the LA Times discusses the allure of Magnesite, although it doesn’t discuss Magnesite’s little problem of asbestos in it… https://www.latimes.com/archives/la-xpm-1999-jul-11-re-54828-story.html