The most important of the minerals mined in Albert County wasgypsum. By the 1930's Albert County produced eighty percent of the total output of gypsum in the Province. The gypsum mined in Albert County was considered to be some of the finest quality gypsum in the world. The Albert Manufacturing Company operated from 1854 until 1980.
During this time the company operated a gypsum mine, four quarries, a private railway, and a plaster mill.
When opened in 1854 the plaster mill was the largest in Canada. From this mill, high grade gypsum was manufactured into plaster and shipped to markets all over of the world. The mill also produced lower quality grey and pink gypsum.
The early mining was done using lanterns and pickaxes, later electric lights and compressed air drills were used.
The gypsum was craved out of the mine walls and then loaded into carts and hauled away by horse to the main shaft of the mine. The gypsum was then hauled in carts to the surface by a cable and winch system driven by a steam engine. Gypsum was also mined from the company's four quarries. The gypsum, from the mine or the quarries, was then loaded onto the company's private trains, nicknamed "Tadd" and "Connie," and transported to the plaster mill. There the stone was crushed into powder and dried in huge bins over wood fired furnaces. These furnaces burnt seven cords of wood a day. That is the same amount of wood required to heat a house for the winter.
The plaster mill burnt to the ground in 1873 and was rebuilt. The rebuilt mill then burned down in 1911. After the fire in 1911 it was feared that the plant would not reopen, however, the plant manager, Charles Osman, convinced the owners in New York to rebuild. The village council of Hillsborough then voted to exempt the company from taxation for the next few years and twelve months later the plant had been rebuilt and was once again operating.
Another important gypsum mining company in Albert County was the Hillsborough Plaster Company. It was purchased in 1924 by the United States Gypsum Company and was closed a few years later. The United States Gypsum Company later became the Canadian Gypsum Company. The Albert Manufacturing Company was purchased by the Canadian Gypsum Company and closed in 1980.