Fergusonite and Gadolinite, Llano County, Texas
Gadolinite is a rare earth Nesosilicate
In photo, the darker, black mineral
Chemical Formula: Y2FeBe2Si2O10
Crystal System: Monoclinic - Prismatic
Fergusonite is a complex oxide of various rare earth elements
In photo, the greenish fractured masses
Chemical Formula: (Y,RE)NbO4, where RE is rare earth in solid solution with Y
Crystal System: Tetragonal - Dipyramidal
Locality: R. A. Rode Ranch Pegmatite, Llano County, Texas
Specimen size: 4.5 in x 3 in x 3 in
Specimen weight: 666 grams
In the Arthur E. Smith Collection, Wheaton College, Wheaton, Illinois.
Additional Information: These minerals were found on a ranch 23 miles from the famous Baringer Hill pegmatite, locality renowned for many rare earth minerals.