Specimens of the Mary Johnson Collection (Part 1)

Mary Johnson, as pictured below, started collecting specimens at the age of 4 or 5 with a chance-collected pebble with prominent veins. Her collecting continued into elementary school where she would collect winged Devonian brachiopods during recess. When her family moved to California at age 13, her primary mineral sources shifted to Concord Lapidary and Frazier’s Minerals in Berkeley. In fact, many of the specimens in this collection were purchased from these two locations.

On the left are two mineral information cards for gold and copper specimens, and on the right is an example of the data taken from thousands of handwritten note cards. This collection has been well documented, with an informational note card created for each specimen.

Mary Johnson based her mineral organization system after the collection found at Caltech. It was there where she would obtain a geology degree, although her original goal was a degree in astrophysics. This was her first choice due to her interest in galaxies and visits to the Palomar Observatory at Caltech, where extraterrestrial images were readily available.

However, she shifted her focus over to the field of environmental science due in part to the high level of sexism and lack of jobs within the field of astrophysics. She also enjoyed trips to the field and soon acknowledged that geology was her preferred science. While at Caltech, she also made her own translated annotated index to Hintze’s Handbuch der Mineralogie due to the disappointing lack of silicates within Dana’s System of Mineralogy.

This is a vibrant pyromorphite specimen from the Daoping Mine in the Guangxi Zhuang Autonomous Region of China. Mary Johnson acquired this at a fall show from the company Geoprime, shortly after pyromorphite minerals were initially exported from China. This piece has ragged crystal tops, but good translucency and color.

Mary Johnson enjoys collecting by chance, which has added great diversity to her collection. She also looked out for specimens with a high refractive index, tetrahedrites, metallic sulfides, perovskites, ruby silvers, green-to-black diopsides, azurites, and malachites. Tetrahedrites were of particular interest, as the focus of her PhD was in the bonding, optical spectrum, and composition of tetrahedrites. In addition, she enjoyed pieces with a good story.

The above and below specimens of kyanite are from Celo Mine in North Carolina. Kyanites are typically found in metamorphic rocks including schists and gneisses, and form as a result of the high-pressure alteration of clay minerals.

The presence of kyanite indicates metamorphism deep in Earth’s crust where both pressure and temperature are high, which include areas where mountain building events occurred. This is one reason why the occurrence of kyanite roughly follows the Appalachian Mountain range, as well as the mountainous west, which has a rich orogenic and tectonic history.

The above specimen was collected from the Kvanefjeld Uranium mine dumps in Illimmaasaq, Greenland on a Caltech alumni tour. During this tour, Mary and her husband walked with a guide and mineral collectors to the mine from the town of Narsaq in southern Greenland.