Some are formed high in the clouds in frosty cold, while others deep in the earth in the intense heat of magma. The former are just a few hours old and invade entire countries in large quantities, while the latter are billions of years old and hide in only a few places on Earth. Some settle like gifted jewels on the winter coat, so delicate that the slightest breath can destroy them. Others are painstakingly crafted into jewelry and are the hardest and most durable materials we know. Yet both grow according to fixed natural rules, in similar sizes, are predominantly white, reflect light brilliantly, and refract it into its spectral colors. Snowflakes and diamonds are minerals, crystalline chemical substances, wonderful forms from nature's treasure trove. They have emerged from interactions between tiny elementary particles, of which there are trillions.