Chrysoberyl crystals, a selection of specimens of this crystallized mineral species. Chrysoberyl is a mineral, and alexandrite is one of its varieties. Here you’ll find a number of collector’s items, each with a description, one or more photos and sometimes a video. These chrysoberyls are for sale. It’s a beryllium-aluminum oxide with the chemical formula Be(AlO2)2 and an orthorhombic crystal system.