“Plaster of Paris” is made from gypsum. Gypsum is a chalk that is a hydrated sulfate of calcium which occurs naturally in sedimentary rocks.
The definition is gypsum a heavy white powder that is heated to high temperature below the melting point or fusion point to extract the moisture, which, when mixed with water, forms a thick paste that sets quickly; used for casts, moldings, statuary, etc…
And found in those mines along with gypsum was the precious Alabaster, which was used to make perfume bottles. The "rose rock" which is found in Oklahoma in more abundance than any part of the world is gypsum.
The mining of gypsum left underground passageways which were under the Basilica of Sacre’- Coeur, a Roman Catholic Church, which is a popular tourist sight of Paris. Sacre’ - Coeur has been reinforced by the city of Paris so it may be enjoyed by future generations. Montmartre is where painters from all over the world gather in "Painter's Square."
Dominique Jean Larvey - used gypsum to stiffen bandages in the Napoleonic Wars or French Revolution on Napoleon’s side.
Louis Seutin was using splints, wetting and starching bandages for casting in the Napoleonic Wars or French Revolution against Napoleon.
Antonius Mathijsen of Belgium while in the Dutch Army made and used “Plaster of Paris” bandages.
Nikolai Ivanovich Piirogov in Crimean War in Russia had seen the use of plaster in Turkey and was using it for bandaging.
From 1790 to 1860 plaster or gypsum from Montmartre in Paris was the highest quality plaster available. Prior to 1860 Montmartre was located outside the city of Paris. The year that it became a part of the city Paris the mining was stopped and the hill was flattened. It was during this time that this chalk was given the name “Plaster of Paris.” In the mid - 20th century “plaster” lost favor in the art and architecture fields. There are many other materials today that are used to replace “Plaster of Paris.” It is doubtful that true “Plaster of Paris” still exists except in the statues, molds and in architecture.