# 🪨 NOTES - GEOLOGY California contains a diverse array of rock and mineral specimens such as serpentine, benitoite, jade, agate, jasper, moonstone, quartz, epidote, and rhodonite. Agate, Jasper, Brecciated Jasper, Pyrite https://rockhoundresource.com/california-rockhounding-location-guide/ https://rockhoundresource.com/best-rockhounding-gear-my-picks/ igneous, sedimentary, or metamorphic An ideal rockhounding day is a receding tide on a non-sandy shoreline after an extra high tide with big surf the day before, and sun coming through to hit the beach. Winter and early spring is generally the best times for rockhounds to collect rocks on ocean beaches. early spring, after a big storm and during a very low tide. Agates are a type of quartz typically found where volcanic activity was (or is) high. They are extremely hard but have a semi-transparent appearance when you frame them in front of ligh A rock is a naturally occurring and coherent aggregate of one or more minerals. Three major classes of rock—igneous, sedimentary, and metamorphic Igneous rocks form from melted rock called magma. Sedimentary rocks are usually made of deposits laid down on Earth's surface by water, wind, or ice metamorphic rocks are subjected to extreme temperatures or pressures, or both, their composition, texture, and internal structure 88 chemical elements known to occur in nature less than two dozen are found uncombined with other elements. This group is called the native elements. Only eight of these native elements are found in significant quantities. The silicates constitute around 25 percent of all known minerals and nearly half of the most common ones. All silicates are built around a basic structure of silicon and oxygen. Chalcedony with distinct banding is called agate Quartz (most common mineral in earths crust) SiO2 QUARTZ: CHALCEDONY A compact variety of microcrystalline quartz Quartz -> Chalcedony -> Agate Most agates are found in cavities in ancient lavas or other extrusive been carved from agate igneous rocks. Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite