A brilliant blue rock bought on vacation as a cheap souvenir is a mineral new to science, geologists confirmed this week. "The mineral has the most intense blue that we have ever seen," said Gordon Cressey, deputy head of the mineralogy department at the Natural History Museum in London. Cressey said Wednesday that the mineral mimicked a stained glass window, changing color from blue to purple to transparent depending on the direction from which light diffracted through it. Geologist Anna Grayson bought the rock, which doesn't have a name, from a roadside souvenir seller in Morocco 15 years ago. The seller told her it was lapis lazuli, a blue semi-precious stone. It sat in her house near London until last year, when she took it to the Natural History Museum for identification. After three months of tests, experts this week confirmed it was a previously unknown mineral. Cressey said about 40 minerals are discovered around the world each year, but usually in amounts so small they can hardly be seen by the naked eye. "This new mineral is so unusual because the specimen is very large and because it is the most strikingly blue mineral ever discovered," he said. Experts will test it in coming months to identify its atomic structure and what, if any, uses the mineral has. So far, a team of seven researchers has found iron, oxygen, calcium, aluminum and silicon in the mineral.