Naturally occurring in marine sedimentary deposits, Greensand is composed primarily of the blue-green mineral Glauconite, an iron potassium silicate. Greensand has been recommended as a soil conditioner since the early 1700's due to its unique physical properties. Traditionally used to loosen heavy clay soil, Greensand is able to absorb up to one-third its weight in water to improve the moisture holding capacity of garden soils and potting mixes. Greensand is highly recommended for vegetables, fruits, herbs, lawns, ornamentals and all types of trees and shrubs.