What classification would a mineral require at 50 ppm fall into?

A mineral concentration of 50 ppm (parts per million) falls into the category of micro-minerals, which are also often referred to as trace minerals. These minerals are required by animals in much smaller amounts compared to macro-minerals, which are typically required in greater quantities, measured in grams or percentages rather than parts per million.

Micro-minerals include elements like iron, zinc, copper, and manganese, and they play essential roles in various physiological functions, including enzyme activities and metabolic processes. The distinction is important because it helps to understand the nutritional needs of animals at different levels. While essential minerals could refer to minerals that the body needs for health, the specific range of concentration is what categorizes the mineral as a micro-mineral in this context. Thus, a mineral present at 50 ppm is classified under micro-minerals due to the low quantity needed for proper biological functions.