To those who find some of the vocabulary a little fuzzy. Here is some clarification.
Rock hounding: the hobby of searching for and collecting rocks, crystals, minerals, and fossils from the natural environment.
Lapidary: relating to stone and gems and the work involved in engraving, cutting, or polishing.
Geology: the science that deals with the earth’s physical structure and substance, its history, and the processes that act on it.
Fossils: any preserved remains, impression, or trace of any once-living thing from a past geological age, such as bones, shells, exoskeletons, and petrified wood.
Crystal: solid material whose atoms or molecules are arranged in a highly ordered microscopic structure, usually identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations. Examples: quartz crystals (often clear or milky), salt crystals (NaCl), or even large gemstone crystals like sapphires and rubies.
Gemstone: (also called a precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or polished, is used to make jewelry or other adornments. Certain rocks (such as lapis lazuli, opal, and obsidian) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) may also be used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some softer minerals such as brazilianite may be used in jewelry
Mineral: a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form. Examples: quartz, feldspar, mica, calcite, and diamond. The “-ite” suffix is also widely used in naming minerals, like hematite and malachite.
Mineraloid: natural solid substances without a definite crystalline structure, e.g. opal or obsidian or one that resembles a mineral, but does not demonstrate the crystallinity of a mineral, e.g. obsidian (an amorphous glass and not a true crystal); lignite aka jet (derived from the decay of wood under extreme pressure underground); and opal (with a non-crystalline nature). Pearl is a mineraloid substance because the calcite crystals and the aragonite crystals are bonded by an organic material.
Rock: naturally occurring solid aggregates composed of one or more minerals (or mineraloids, like volcanic glass), organic materials, or other mineral-like substances. Rocks are made up of various minerals. Example: granite is composed of the minerals quartz, feldspar, and mica.
Leaverite: is a slang term to describe a rock that is interesting, but not worth removing (comes from the phrase “leave ‘er right there”).
Cabochon (aka cab): a rock (usually a semi-precious stone such as quartz, agate, jasper, chalcedony, onyx, obsidian) that has been shaped and polished. The resulting form is usually a convex (rounded) or faceted obverse with a flat reverse.