ENVB 210 Lecture Notes - Lecture 13: Montmorillonite, Chemical Formula, Vermiculite
Document Summary
Isomorphous substitution: creates negative charge in the clay. For this to occur the size, not the charge of the ions matters. The higher the negative charge, the higher the cations exchange capacity (ece) which is the ability to hold cations. Note: those cations are the accessory cations, not those in the crystal structure (unavailable). Highly weathered clay that has lost mg, ca. (found in highly weathered regions) Relatively high negative charge because high rate of si4+ replaced by al3+ very attractive to k+, prevents crystal expansion (layers held tightly with k+) A lot of soils in quebec will have a lot of potassium because of illite clays. Vermiculite: 2:1 the clay with the highest charge (development in the tetrahedral sheet) Used for holding water in potting soils or used for insulation. Exposed to a high heat, layers will separate hold water. However, swelling is limited because the layers are close to cations.