A profusion of small white crystals of sillimanite in biotite matrix in a specimen of biotite-feldspar-quartz gneiss from the Edison mines. Like specimen SIL1b, this specimen likely was collected by Joe Orosz and was donated to the Franklin Mineral Museum by his widow, Sharon, in late 2017. It now resides in the FMM collection as specimen FMM-7929.
Identifier: SIL7a Locality: Edison mines, about 2.6 km southeast of Ogdensburg, in Sparta Township Specimen size: 15 x 8 x 4 cm Photo credit: Elaine Whetstine
