Monday, February 27, 2017

A 20 Pound Vivianite Concretion from Anne Arundel County, MD

It is certainly reasonable to assume that  nature offers few greater pleasures to mineral collectors living in temperate climates than those few unseasonably warm days that  occasionally come once or twice in late February and early March.  Aside from pleasant temperatures, the amount of live vegetation obscuring surface rocks is minimal, while the mosquitoes, ticks, and copperheads remain dormant. Such a day was February 24, 2017, at least in the vicinity of Baltimore, Maryland. 

So for this writer, it was off to search for vivianite in Maryland's Anne Arundel County  along the banks of Harman's Branch. By virtue of a find 77 years ago,  Mindat names the spot as Vivianite Concretion Locality, Riva, Anne Arundel County, Maryland, USA . The information provided, however, proved confusing for pinpointing the specific location. Credit Robert Beard for persistence in finding it to include on page 156 in his Falcon Guide Rockhounding Delaware, Maryland, and the Washington, DC Area © 2015, Rowman & Littlefield.

Notwithstanding,  Tarnan's Branch and its banks are all but devoid of rocks as this muddy rill heads upstream  from Rutland Road along the route taken by Beard. Otherwise, the surrounding wooded landscape lies under several inches of fallen leaves.  Only after about a quarter of a mile where Tarnan's Branch flows into a tunnel beneath a road does one encounter many rocks. Most of them are quartzite  with  no hints of  likely concretions in their midst.  My hour spent here could not have been more in vain. 

With head down, more in discouragement than with the expectation of  uncovering  the likes of a vivianite concretion, I trudged back toward my car parked along Rutland Road. Amidst the leaves, loam, and moss, nothing at my feet hinted at the likeness of  a concretion beyond an occasional dirty hickory shell. So it was until what first looked  like the nub from a tree root protruded from the soil. It was bigger than to be expected from the trees nearby, brown, muddy, and partially covered with dead moss. Upon tapping it with the chisel on my hammer, a half inch piece of shell broke off that appeared black but with a bluish cast. It had to be a concretion. Once unearthed, a hefty whack with my mini sledge halved it to reveal an interior of colors  ranging from  black and, gray, to a paler and more aesthetically pleasing blue. Clearly, this was the same kind of material as pictured on 156 and 157 in Beard's book, 

Never was my knapsack heavier than during that hundred or so yard walk back to the car. On the scale at home, the two halves along with a few loose chips weighed just over 20 pounds. This writer considers himself the beneficiary of sheer luck and has no plans to return to what was  a difficult to navigate locality. One twenty pound vivianite concretion is plenty for my Maryland suite where it will rest in a spot where light, which causes  vivianite to eventually turn black, is minimal. 

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