The Rice Northwest Museum of Rocks and Minerals in Hillsboro, Oregon, houses a world-class collection recognized as the finest in the Pacific Northwest and one of the finest in the United States. The Museum building, originally constructed as the private residence of Richard and Helen Rice, is listed in the National Register of Historic Places for its unique architectural style, natural stonework, and the extraordinary native Oregon woodwork found throughout the building.
One of the bedrooms in the house is now the Agate Gallery which features agates from Brazil, Mexico, and Argentina.
Brazilian agate is found in the southern state of Rio Grande do Sul. This is a large basaltic flood basalt province called Parana. This was formed in an eruption about 130 million years ago. According to the Museum display:
“Most of the agate nodules consist of colorless, gray, brown, black, red, or white bands and layers plus colorless quartz. Hematite, goethite, and manganese oxides inclusions account for most of the color. Alterations of the primary coloring inclusions by oxidized ground water dissolves some of the black manganese oxides and turn the iron oxides bright red.”
More Minerals
Mineral Museum: Quartz (Photo Diary)
Mineral Museum: Meteorites (Photo Diary)
Rock Museum: Some Minerals from Brazil (Photo Diary)
Museums 101: Some Minerals (Photo Diary)
Museums 101: The Hixon Gem Vault (Photo Diary)
Museums 101: South American Gems and Minerals (Photo Diary)