These samples of amblygonite are displayed in the Smithsonian Museum of Natural History. Amblygonite is a phosphate mineral which is a minor source of lithium . It has the composition (Li, Na)AlPO4(F,OH). This sample is about 10 x 20 cm and is from Lavra da Ilha, Taquaral, Minas Gerais, Brazil.
Amblygonite occurs only in pegmatites. It rarely shows its crystal shape as clearly as in this pale yellow-green specimen with sprays of eosphorite.
Amblygonite is the fluoride analog of montebrasite.