Gemstones associated with metamorphic rock include beryl, jade, lapis lazuli, turquoise, spinel, ruby, sapphire and zircon. Rocks and minerals are in a constant state of change, which is referred to as the rock cycle. Igneous rock can change into sedimentary or metamorphic rock.
Lime is a soil amendment made by grinding limestone, a naturally occurring type of rock that is very high in calcium. Two types of lime are commonly used in lawns and gardens, agricultural lime and dolomitic lime. Agricultural lime, also sold as garden lime, is made from calcium carbonate.
It crumbles rapidly and easily. Marl in which the lime is in the form of invertebrate shells is called shell marl. The term is loosely used for a variety of soils, some of which are low in lime content, e.g., the greensand marl of New Jersey. Marling of soil tends to lighten it, correct acidity, and promote nitrification.