Grandidierite is a rare mineral known for its striking blue-green color, often found in Madagascar. It is a borate mineral that typically forms in metamorphic rocks and is prized by collectors for its unique hue and transparency. Grandidierite is often used in jewelry, although its rarity makes it less common in commercial pieces. The mineral was first discovered in 1902 and named after the French explorer Alfred Grandidier, who studied Madagascar's natural history. Grandidierite has a hardness of 7.5 on the Mohs scale, making it relatively durable for use in various applications, including gemstones.