Specimens of the Mary Johnson Collection (Part 2)
Mineral specimens donated by Mary Johnson that include chrysocolla specimens, fluorites, and wavellites.
By Mineralogical and Geological Museum, Harvard University
Credit to Lucia Cheney
Here is a brightly colored and stunning Azurite specimen with shiny radial blue crystals, collected from Yang Chweng Mine in the Guangdong Province of China.
Mary acquired this azurite specimen during a benefit auction to provide better lighting for the mineral rooms at the Harvard Mineralogical Museum. Although this specimen was in high demand, the weather during the event was particularly poor, so with luck, she was able to purchase it before other interested parties arrived. She was drawn to this specimen as it “looks like the southbound end of a northbound turkey,” as well as azurites of this type being very “clean looking.”
A purple-blue twin fluorite from Namibia. These penetration twins form when two cubes collide during formation.
Fluorite from Murquiz, Coahuila in Mexico. The mineral fluorite occurs in various habits, with a colorless or transparent color. However, impurities often make these quite colorful.
A stunning Chrysocolla and Hemimorphite wad is shown above, originally from the 79 Mine in Arizona, but acquired at a Montana rock shop.
Above is a Krohnkite and Antlerite sample from Chuquicamata Mine, Chile. Mary acquired this specimen from the collection of L.C. Wyman, which Harvard received initially. Present in this specimen is Krohnkite which shows as blue, and Antlerite as green. The fibers are primarily continuous and the color change represents a reaction front.
One of many fluorites in this collection. From Xianghualing Mine, Chenzhou Prefecture, Hunan, China.
Shown above and below are wavellites from Montgomery County, Arkansas. This is a secondary mineral found most often in aluminous, low-grade metamorphic rocks.
Although wavellite is not a major industry mineral, it is used in industrial processes to separate phosphorus from iron ore. Phosphorus is seen as an impurity in the steel making process. The separation of phosphorus content is “achieved through reverse flotation making use of anionic collectors to float the apatite and sodium silicate to depress the iron oxides” (Nunes et al.).
This Calcite is from Cantung Mine in the Northwest Territories of Canada, collected by Mary Johnson in the field.
It was in Canada’s Northwest Territories where Mary Johnson had the opportunity to visit diamond mines for the first time. During one of these visits to Diavik’s A415 South diamond pipe, she separated from her group which proved to be especially dangerous as she was caught in a diamond-rich kimberlite quicksand. Thinking quickly, she had to throw herself on her back to get free.
The diversity of types of specimens found in this collection range beyond minerals and include organic specimens, synthetics, and simulants. Some organic specimens not included in this online exhibit include a wasps nest, a horse's kidney stone, and whewellite, which is a product of bacteria and fungi. Moolooite is also included, which results from the interaction of fossilized bird excrement and weathering copper sulfides.
Lucia Cheney, Mary Johnson
Nunes, Aline Pereira Leite, Cláudio Lúcio Lopes Pinto, George Eduardo Sales Valadão, and Paulo Roberto de Magalhães Viana. "Floatability studies of wavellite and preliminary results on phosphorus removal from a Brazilian iron ore by froth flotation." Minerals Engineering 39 (2012): 206-212.
