A brooch stone is a type of jewelry that is typically pinned to clothing. It often features a gemstone or other decorative element. Two popular types of brooch stones are AGATE and OPAL. AGATE is a type of quartz that comes in a variety of colors and patterns, while OPAL is a type of mineraloid that displays a rainbow of colors when viewed from different angles. Both AGATE and OPAL are popular choices for brooch stones due to their unique beauty and durability.