👉 Ceruleite is a mineral that occurs in the Earth's crust as a grayish-white to yellowish-green crystal. It is also known as "sapphire" or "ruby". Ceruleite is composed of two rare-earth elements, yttrium (Te) and lanthanum (La), with a slight amount of strontium (Sr). The mineral has been used for centuries in various applications due to its unique optical properties.
