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.
Pickling Lime is Calcium Hydroxide. It's also called food-grade lime, because in making the Calcium Hydroxide the processors make sure that the process remains pure and doesn't introduce anything untoward (e.g. it's not done in rusty old bins.)