Plants absorb minerals in ionic form: nitrate (NO3−), phosphate (HPO4−) and potassium ions (K+); all have difficulty crossing a charged plasma membrane.
In animals, minerals found in low small amounts are microminerals while the seven elements that are required in large quantity are known as macrominerals; these are Ca, P, Mg, Na, K, Cl, and S. In most cases, minerals that enter the blood pass through the epithelial cells which line the gastrointestinal mucosa of the small intestine.
Minerals can diffuse through the pores of the tight junction in paracellular absorption if there is an electrochemical gradient.
Through the process of solvent drag, minerals can also enter with water when solubilized by dipole-ion interactions.
[1] Furthermore, the absorption of trace elements can be enhanced by the presence of amino acids that are covalently bonded to the mineral.