👉 In geology, a rhyncholite is a type of mineral that occurs in rocks and is formed by the dissolution of sulfuric acid. It is a grey or brown-colored mineral with a smooth surface and has a rough texture. Rhyncholites are found in a variety of rock types, including igneous, metamorphic, and sedimentary rocks. They can be found in both marine and terrestrial environments, although they are most commonly found on the ocean floor.