When sourcing mineral blocks, the chemical composition and density are paramount. Ensure the block contains a balanced ratio of Macro-minerals (Calcium, Phosphorus, Magnesium) and Trace elements (Zinc, Copper, Manganese, Selenium, Iodine). For high-performance livestock, the salt (NaCl) content usually acts as the carrier, but the hardness of the block must be sufficient to prevent over-consumption; it should withstand weathering and rain without crumbling. Always request a Certificate of Analysis (COA) to verify the purity and concentration of ingredients.