The Kennebec Historical Society’s May presentation, “Oxford County Gem Bearing Litha Pegmatites,” will begin at 6:30 p.m. Wednesday, May 17, at the Maine State Library, 230 State St., in Augusta.

Oxford County is world-famous for its pegmatites and the minerals it produces, according to a news release from the society. Granite pegmatites are coarse-grained, igneous rocks that contain large crystals of feldspar, mica, quartz and sometimes a suite of rare earth elements and gem-quality minerals.

The most ‘spectacular’ crystals are found in “pockets,” or open cavities in the rock, that allow minerals to grow unimpeded. Minerals there tend to have few flaws.

Three generations of the Perham family have mined the pegmatites of Oxford County from a number of different quarries according to “The Perham Family Quarries,” an article by Sydney D. Eckert in the July 2014 issue of the Maine Geological Survey.

In the early 1920s, the nearest feldspar processing mill was in Auburn. It was not economical to transport the feldspar that far. Alfred Perham, with the help of some local investors, constructed the Oxford Mining and Milling Company plant in 1924 to process the feldspar mined in the area by the Perhams and others. The mill operated into the late 1960’s.

Perham’s son, Stanley Perham, opened his store in West Paris in 1919. It welcomed visitors from every state in the nation and from countries all over the world. Stanley passed on his love of minerals and business sense to his children, Frank and Jane.

Frank Perham, the May 17 speaker, was lucky to come from a line of Maine miners, but he relied on more than just his luck to make a name for himself in the mineral community. He trained as a geologist at Bates College like his father. He has spent a lifetime in the mines and has his own mineral museum, The Mineral Pocket. He has a vast amount of knowledge and the respect from geologists and enthusiasts alike to show for it. He is 83 years old and still does some summer weekend mining.

The presentation is free, though donations are gladly accepted.

For more information, call 622-7718.