What minerals are found in the ground here that are (or were) economically valuable? Q26 of The Big Here Quiz

Halite (natural salt) and Anhydrite

Ojibway Mine, Windsor, Essex Co., Ontario, Canada
ref: Geological Survey of Canada Miscellaneous Report 39.
In dolomitic limestone and limy shale. The main salt bed is 8.2 m thick and is at a depth of 289 m to 297 m below the surface. Another bed is 9 m above it. The salt is exceptionally pure containing less than 2 per cent impurities. The salt beds occur in the Salina Formation of Silurian age.

Sulfur

Amherstburg Quarry, near Windsor, crude large xls;
5 localities in R.Traill, Cat.of Can.Mins., GSC Paper 80-18, 1983

[In the mid 1800's, thousands came to Windsor every summer to visit the sulphur springs in Brighton Beach, just outside of Sandwich... more]