In northern michigan we have beach slags from 1840-1880 charcoal furnaces. The light baby blue slag is known as Leland Blue ( Lehand is furnace name and location) and is popular with artists. There is a debate on the source and nature of the color. Most charcoal furnaces in US are green, brown, or rarely very dark blue. Leland Blue slag is similar to “Swedish Blue slags” sold here as well. does anyone know the analysis of these Swedish slags or the nature of their color?
another popular slag is light green “franklin” green from a nearby furnace
