Monday, May 23, 2016

Maryland Topaz and Maryland Chrome Tourmaline

Additional new images of Maryland-collected minerals are now gracing the slide show on our Maryland Minerals website. More are on the way. They are from the collection of the Natural History Society of  Maryland. It is surely one of the largest and most diverse collections of Maryland-collected minerals in existence. The most glamorous of the specimens are displayed  at the Society's Headquarters at 6908 Belair Road in Baltimore. The Society has stored and preserved hundreds more. Many are the bounty of field trips dating back over 70 years.

If less spectacular to look at than the minerals on display, many of those additional hundreds are highly significant from a scientific and/or historic vantgage point. Included are dozens  of the only known examples of their species to document occurrences named at scores of localities mentioned in the Society's 1940 publication Minerals of Maryland. Often the labels credit one the co-authors, Charles Ostrander or Willaim Price,  with the finds. Two particularly interesting pieces are gem minerals.

The only reference to topaz in Minerals of Maryland is from Alto Dale Farm, which covered several acres at the southeast corner of Reisterstown Road and Cradock Lane in Baltimore County. Houses have completely covered the site for decades. The description noted "white cleavage masses" with quartz crystals" in "soil weathered from a pegmatite dike." The one pictured is the more impressive of two owned by the NHSM. They could well be the only known Maryland-collected topaz specimens in existence.

Another remarkable gem mineral is the chrome tourmaline at right. It is from the Etchison Chrome Mine in Montgomery County. Minerals of Maryland credits this find to the late mineralogist Earl Shannon (1895-1961). It describes the mine circa 1940  as "not been worked for many years, and little of interest remains at the site." The owner was Baltimore's legendary chromium mogul  Isaac Tyson, who also owned the operations at Soldiers Delight, Bare Hills and others extending northeast into Lancaster County, Pennsylvania. Heyl and Pearre later reported chrome tourmaline from the Line Pits, Rock Spring, Maryland. That find, however, lacked the color and luster of the Etchison specimen, Moreover, it is possible that the Rock Spring chrome tourmaline originated in underground workings on the Pennsylvania side of the State Line. Much that was mined there ended up on Maryland bases pits.

Topaz and chrome tourmaline are but two specimens out of nearly 50 NHSM pieces begging to be photographed as well as subject matter for stories.

1 comment:

  1. It would be interesting to make a modern analysis of the "chrome tourmaline" and determine the species. Chromium-dravite? Chromo-aluminopovondraite?