Clay between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. Mixtures of sand, silt and less than 40% clay are called loam. Loam makes good soil and is used as a building material. Clay minerals typically form over long periods of time as a result of the gradual chemical weathering of rocks, usually silicate-bearing, by low concentrations of carbonic acid and other diluted solvents. These solvents, usually acidic, migrate through the weathering rock after
Serpentine soil tolerant of extreme soil conditions, including: Physically these areas are characteristically steep, rocky, and vulnerable to erosion, which results in shallow soils. The shallow soils and sparse vegetation lead to elevated soil temperatures and dry conditions. Serpentine is a unique classification of soils as they are relatively rare, and exhibit distinct chemical properties. The soil in appearance is often reddish, brown, or gray in color. The parent material for serpentine soil is mostly derived from the rock serpentine, noted for its waxy greenish-silver to bluish-silver appearance. The rock has white streaks of mineral running through it that contain naturally occurring