The mineral content of Alberta water is one of the highest in the country, possibly North America. Salt, aquarium salt, is sodium chloride (NaCl), which is part metal and part chlorine- no minerals there. This ionic compound is not normally natural in fresh water and it's even rarer in South American black water to which oscar evolved in. I am also yet to find any information anywhere as to how the continued use of salt in freshwater tanks is good for a fishes health. And brackish water or esterine water is salt water, but at a lower salinity than marine water.
A mineral is a naturally occurring solid chemical substance that is formed through geological processes and that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not have a specific chemical composition. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms.
Under this definition I think salt classifies as a mineral. Salt isnt always made with a Sodium ion either. It can be MgCl2 such as what the main composition of the salt in the ocean is.