The lease on the site was taken from the Duke of Bedford in 1844 by a group of investors, Sanderson & Co., that included the father of William Morris.

Work at the site began in August of the same year, when it was known as North Bedford Mines or Wheal Maria.

By November 1844, a rich vein of copper ore was discovered at a depth of 20 fathoms (about 36 metres) under ground.

After learning that the copper lode extended eastward for over two miles (over 3 km), the company quickly began opening other mines on its property.

The mine was so productive that transport by horse and wagon could no longer handle the volume of copper it sent to the docks at Morwellham Quay.

When cheaper sources of copper became available from abroad, the company began refining arsenic in 1867 and was considered to be its largest producer in the 19th century.

[2] Led by Josiah Hugh Hitchens, a group of six[3] investors who were comfortable with the risks in establishing a new copper mine, agreed to fund the project with £1,024.

[4] The group met the Duke of Bedford's land agent and signed a lease for the property on 26 July 1844.

[12] Because of the amount of ore the mine produced, transporting it by horse and wagon soon proved inefficient.

The company built its own five-mile (8 km) railway; it was completed in November 1858; this linked the mine with Morwellham Quay for the export of ores.

[13] Devon Great Consols owned three locomotives and 60 wagons, which transported ore to Morwellham Quay and also brought equipment and supplies such as coal, to the mine.

[13][18] The Devon Great Consols dock was restored in the latter part of the 20th century with the bollards and portions of a crane from the quay surviving.

[25] The mine fell victim to low prices for arsenic and a need for capital for both improvements and exploration.

Despite this, the Duke of Bedford renewed the lease on the land, giving the company an opportunity to recover from its losses.

[29] The site was active again for a period of time during World War I, when arsenic was needed to produce blister gas.

The post-war slump brought an end to mining tungsten and tin at Devon Great Consols, but arsenic production continued until 1930.

[33][34][35] The original arsenic works and cottages at Wheal Josiah became Grade II Listed buildings on 23 January 1987.