Minnesota has several important non-renewable natural resources. According to the map and its key, all BUT ONE of the natural resources listed here is mined in Minnesota. What is that resource that is not mined? A) clay B) iron ore C) limestone D) industrial sand

Clay is not mined in Minnesota.

Explanation:

Minerals that are found in Minnesota are broadly categorized into two types - metallic minerals and industrial minerals. Metallic minerals divided into ferrous mineral which contain iron and non ferrous minerals donot contain iron but it contain other metals like copper. Metallic minerals contain iron ore, where as non ferrous minerals contain manganese, copper, nickel, platinum, titanium etc. Industrial minerals include sand, gravel, peat, landscape stone, silica sand, limestone, china clay etc. Some times, different bedrock are mined like quartzite, granite, gabbro, gnesis etc.