brimstone - an old name for sulfur. native sulfur, native sulphur. atomic number 16, sulfur, sulphur, S - an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions)
These patches of red, and sometimes irritated or itchy, skin can appear anywhere on the body, but they are most commonly found on the arms, neck, and face. These blotchy patches can be caused by a variety of factors, such as weather, genetics, allergies, or environmental conditions.
Allergic reactions to some foods, plants, or even the irritants might also result in the discolored skin patches in various areas of the body. These changes can present as the rashes or raised bumps that normally itch or burn. One common allergy that might cause skin black spots on skin is the eczema. Like certain autoimmune diseases, eczema usually triggers an immune reaction that attacks the skin. The condition can lead to scaly patches and the red bumps that ooze or crust over.