Saturday, August 29, 2009

Maryland Minerals at the Harvard Museum

Never has a display of minerals rendered me so spellbound as the Harvard Mineralogical Museum in the Harvard Museum of Natural History at 24 Oxford Street, Cambridge. Some displays seek primarily to grab the attention and interest of the general public. Others seek mainly to educate. Many want to dazzle and amaze if they have the goods. Created from a frame of reference for education, research, and public display, the Harvard Mineralogical Museum does it all, albeit with but two specimens from Maryland.

The Harvard Collection is old school. Its main room consists of rows of ancient chest-high glass-topped wooden cases with the minerals displayed beneath them. The minerals, usually hand-sized, rest atop a rustic looking muslin fabric that's not always well-vacuumed. Upright glass cases with larger specimens hug the surrounding walls. The minerals are arranged systematically according to chemical composition.

My first Maryland observation was a small clear glass dish of octahedral chromite crystals from Bare Hills, where chromite was first discovered and recognized in the United States. The container of crystals was displayed amidst specimens of chromite with different morphology and habit from other localities. Once part of the L. Liebener collection, they were probably assembled in the first half of the 19th century. I would love to know how these crystals were collected. Did they occur as floaters in the soil or were they extracted from a (presumably serpentinite) matrix? Although massive chromite has always been ubiquitous at the Bare Hills serpentine barrens, crystals are most unexpected.

The other Maryland specimen that I observed was massive rockbridgeite within a concretion. It was collected at Greenbelt in Prince Georges County. This particular specimen fascinated me because my personal collection features a similar piece from this locality that I obtained a couple years ago through Fred Parker. Just like my specimen, it bears additional brownish phosphate minerals. They could include dufrenite, kidwellite and beraunite, a combination once known as laubmanite, a discredited mineral. Leaving such considerations to the Museum’s research and education components, the label heralded only the gray-black rockbridgeite, which like crystallized chromite, is not often contemplated as occurring in Maryland.

The Harvard Mineralogical Museum's web site notes that about 4,000 minerals are on display. This seemed like a lot unless I missed something, which I did, because the entire collection exceeds 50,000 specimens. Most are arranged paragenically instead of systematically and are housed in "readily accessible drawers." With over 4,000 specimens from the Franklin,New Jersey environs, and 7,000 New England pieces, it’s likely that Harvard has additional Maryland minerals. What a treat the prospect of snooping through those drawers. Next visit, additional time will be available, and I'll have researched the protocol.

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