Howlite is a borate mineral composed primarily of calcium borosilicate (Ca₂B₅SiO₁₉). It is usually found in a white or grayish-white color with veins of gray or black, giving it a marble-like appearance. Howlite is a relatively soft mineral, with a Mohs hardness of 3.5, making it easy to carve and polish. It is often used as a substitute for turquoise in jewelry and is commonly made into beads, cabochons, and ornamental carvings. Howlite is primarily found in North America, particularly in California, as well as in parts of Turkey.