History of Gilsonite

The mineral now knows as Gilsonite or Asphaltum was discovered in the early 1860’s, but it was not until the mid-1880’s that Samuel H. Gilson began to promote it as a waterproof coating for wooden pilings, as an insulation for wire cable, and as a unique varnish. Gilson’s promotion of the ore was so successful that, in 1888, he and a partner formed the first company to mine and market gilsonite on a commercial scale.

Originally, Gilsonite was sold as “Selects” and “Fines”; the low softening point ore with conchoidal fracture was known as “Selects”. The higher softening point ore with a pencillated structure was known as “Fines”. Selects commanded a higher price than Fines because of its better purity, good solubility, and usefulness in the paint, stain, and varnish industries.

Time and technology have changed this classification system. Processing of Gilsonite now removes most of the inert contaminants and newer, more powerful, solvents make the higher softening point grades more interesting to the user. Today, Gilsonite is graded by softening point (a rough measure of solubility) and particle size. All grades carry a degree of quality far superior to those first small amounts of crude Gilsonite marketed in the 1880’s.