Thursday, October 13, 2016

Baltimore County's Historic Milford Trap Quarry

In northwestern Baltimore County, the  Milford Trap Quarry's historic legacy has continued to evolve for the better part of a century since the last of its mineralogical bouny was taken. Those familiar with the site along Milford Mill Road near the Baltimore City line will recall the fire that destroyed a mosque built there  two years after the site sold at auction in 2013. At times between 1950 and then, the old quarry was the focal point of a swimming club along with a teen center and bandstand. The Buddy Deane Show happened there at least once, and scenes from from John Waters' Crybaby and Barry Levinson's Liberty Heights were filmed there.  

Less remembered is the wide range of collectible minerals that the Milford Trap Quarry produced. The Natural History Society of Maryland's long out of print yet still penultimate  guide to Maryland minerals, Minerals of Maryland mentions  "minerals to be found" there in the present tense, suggesting that collecting was still taking place upon its publicaton in 1940. With the exception of Hunting Hill in Montgomery County, which had yet to be "discovered," few if any Maryland localities produced as many different species. Rarely do specimens from the Milford Trap Quarry grace collections or displays. 

The good news is that the Natural History Society of Maryland  has saved and thus preserved what surely must be the premier assortment of Milford specimens as described in Minerals of Maryland. Many appear to be original reference specimens upon which the publication depended.  Early in 2016, the Natural History Society allowed access to many of these long stored away specimens. Among them were many that were particularly notable. 


As ubiquitous as chlorite is at numerous Maryland localities, this one stands out in itsw habit.


This pyrrhotite specimen is notably rich compared to other specimens that have been uncovered in Maryland.  Most Maryland pyrrhotite occurs in a matrix of limestone. Here, it is seen gracing gabbro.


After it had been stored away for many decades, we uncovered this  specimen of the zeolite group mineral laumontite. It is paricularly important for having been the specimen photographed for the inside cover of Minerals of Maryland. 


At the time Minerals of Maryland was published, the Milford Quarry was the only locality in Maryland to have reported scoleite, another zeolite mineral, The species was later uncovered at Hunting Hill in Montgomery County, which is now off limits. The crystals from Hunting Hill, however, were smaller and less showy. We have every reason to believe that this is the finest scolecite specimen ever uncovered in Maryland.


Prehnite is no a zeolite mineral, but typically associated with zeolites and erroneously thought by many to be one. The Milford Quarry was prehnite's only known Maryland locality for nearly a half century. 


Though a common species found at numerous localities, the occurrence of this particularly rich specimen at the Milford Quarry is notable.


Minerals of Maryland notes sphene at the Milford Quarry in "green and brown crystals." Pictured above is a specimen of sphene in green and brown crystals in a matrix of feldspar and metagabbro. 


Clinozoisite as shown above was known to have been abundant at the Milford Quarry and thought to be zoisite. The visual distinction when in this habit is difficcult to make.   

Minerals of Maryland mentions other species known to have been collected  the Milford Trap Quarry  as follows:

Platy ilmenite; pyrite in masses and in crystals; stilbite, natrolite; calcite crystals and cleavages; flattened garnets; black tourmaline crystals; albite; quartz crystals up to five inches long; marcasite crystals and stalactic forms in cavitites; magnetite massive and in brilliant octahedral crystals 1/4 inch across; rutile crystals; horneblende crystals in quartz three inches long; chalcopyrite; radiated actinolite; pyroxene; prochlorite (chromian clinochlore); analcime crystals; laumontite pseudomorph after analcime; epidote in long bladed single crystals and crystalline masses; mizzonite (scapolite); molybdenite; andesine crystals; radiated phillipsite; talc pseudomorph after actinolite; and muscovite.