The three types of rocks igneous, sedimentary, and metamorphic are all subject to processes that change one rock type into another. The images below show several types of rocks undergoing these processes.
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.
Fertilize, water deep when the grass needs it, mow high and often (next Spring), and minimize foot traffic until it recovers. You should also put a thin layer of compost as a top dressing over your lawn (particularly the brown patches) to improve the soil and microbial activity.