Windsor Gypsum Company

The Windsor Gypsum Company operated a quarry in Hants County in the late 1800s and early 1900s.

The quarry was opened around 1891, one mile northwest of Newport at that time, or five miles east of Windsor.

A 1915 report described the quarry as being on a 180-acre property. A rock face of 20 feet was being worked and the quality of the gypsum was “a splendid grade.”

The gypsum was drilled by hand augers. Blasting powder and a low grade of dynamite were inserted in the drillholes and set off to free the gypsum from the rock face. The blasted rock was then loaded into horse-drawn carts and hauled two hundred yards to a railway siding that connected with the Dominion Atlantic railway, which hauled it to the company’s shipping pier in Windsor.

In 1906, almost all of the quarry’s output was taken by New York’s Higginson Manufacturing. The company was named for H. C. Higginson of Newburgh, New York, who also operated a gypsum quarry on Cape Breton’s Isle Madame in the late 1800s and early 1900s ( Gypsum is the main ingredient in Plaster of Paris, which was used for things like mouldings and medical casts, and Higginson used Nova Scotia gypsum in his plaster products.

In 1912, part of the quarry’s production was shipped to the Windsor Plaster Company’s calcining mill in Windsor, and the balance was shipped to the United States. The Windsor Plaster Company operated a number of historical quarries in Hants County and, somewhat unusually for Nova Scotia, a calcining mill. Calcining gypsum means to heat and partially dehydrate it. This is part of the process of turning gypsum into plaster. (Learn about the Windsor Plaster Company and how calcining works at

The Windsor Gypsum Company quarry was also known as the Mosher Quarry and Thomas A. Mosher was its manager in the early 1900s. Miss Effie Mosher became its manager in 1923 – unusual for a woman in that era - and oversaw the quarry’s most productive years. The quarry’s biggest years of production were 1924 (27,423 tons of gypsum produced) and 1925 (27,300 tons).

An updated version of the 1915 report, which was printed in 1930, said the property had grown to 225 acres and the working face on the north side of the quarry was over 350 feet in length with a height of 40 feet. The overburden, the dirt on top of the gypsum deposit, averaged 20 feet and was stripped off by a steam shovel and hauled to a waste dump by a Fordson tractor operating on narrow gauge tracks.

The report notes that the gypsum was being broken down to “man size.” Before mechanized loading, ships were loaded by hand. There was a standard rock size called a “one man-rock,” or “man-sized rock,” meaning a rock that an average-sized man could carry from the wagon to the ship (i.e. about the size of a basketball). The term became a unit of measurement in the industry and it’s still used in some places to describe the size of stones used in landscaping (i.e. a one-man rock, a two-man rock, etc.).

In 1930, the blasted gypsum was hauled to a loading platform and loaded into standard-gauge open rail cars on tracks laid into the quarry from Newport Station. The rail cars were hauled to Newport and from there to the company's wharf at Windsor, where the gypsum was loaded onto steamers for shipment to Newburgh, N.Y.

The quarry ceased production in 1934.

Before wallboard/drywall became the most common way to finish walls, walls were usually made of laths (thin, flat strips of wood) with plaster spread over them. Ground gypsum was, and still is, a key ingredient in plaster. This method of making walls died out after wallboard was invented in the United States in 1918 by sandwiching plaster between two sheets of paper.

Today, wallboard is used in most buildings. An average home has about seven tons of gypsum in its walls. Most walls in Nova Scotia contain gypsum quarried in the province.

Safety is the main reason gypsum is in wallboard. Gypsum is 21% water at the molecular level so it slows the spread of fire and helps save lives.