Even blue rocks and minerals, like sapphires and lapis lazuli, are hard to come by. And blueberries were even more of a ...

In general, mineral particles are small, having formed within confined areas such as lava flows or between grains of sediments. Large crystals found in geodes and other rocks are relatively rare.

These minerals are often particularly sensitive when exposed to ultraviolet (UV), blue light or inappropriate relative humidity. 'Many people think that because rocks are usually hard and have lasted ...