Blue Dumortierite Slab americandendrites They are three-billion-year-old mats of

They are three-billion-year-old mats of cyanobacteria (blue-green algae)

The tube forms were colored golden orange to red by their replacement minerals

Though referred to as a jasper

dusty pink background

this stuff has a reputation for being a bit vuggy and this slab is no exception

Blue Dumortierite Slab americandendrites They are three-billion-year-old mats ofDumortierite can sometimes be mistaken for sodalite and lapis lazuli; however, it's harder than both of those materials and therefore more durable for jewelry; it's also likely to take a higher polish. It displays a fantastically rich, denim blue color a great way to get such a vibrant color in a relatively hard material (MOHS 7 8). This is a rough, unpolished slab. Please observe images closely for flaws, as some degree of that is normal. Pictured