You wrote:
>
>At 11:23 AM 1/23/96 -0500, Jason Menard wrote:
>
>>        Slag can take many forms, from what you described, greyish,
burnt,
>>vitrifed in places, to forms that basically look like lava rock, for
lack
>>of a better descriptor, ranging from black, to rustish brown. I've
even
>>seen iron slag that glassy-green in color, almost completely
vitrified-
>>although this may be the result of workers tossing in items into the
forge
>>in operation, and not from the content of the ore used.
>
>I'm interested in the "glassy-green in color, almost completely
vitrified"
>material mentioned in association with iron slag and forge operations.
I
>have been told that this may be the by-product of using a limestone
flux in
>the forging process, or perhaps in combination with limestone linings
of the
>forges themselves. Does anyone have any further information about the
>archaeological association, context, and physical structure of this
>glassy-green slag? Is it usually found with metal forging features?
Has it
>also been observed in  other high temperature manufacturing contexts
such as
>cement, ceramic, or glass making?
>
>Thanks in advance,
>
>--Lenny__
>
 
Here in Connecticut where we have both early bloomeries (btw, a
bloomery is a large forge, usually with a large wheel driven
trip-hammer, where iron ore is reduced through the old heat-n-pound
method vs. the furnace method, where impurities are removed by heating
the ore to a molten state, and impurities are carried to the top by a
flux, usually limestone) and iron furaces (Saltonstall was the 3rd
_successful_ furnace in British North America).  The slag we had at the
Falls River Bloomery in Centerbrook (where ironically, my direct
ancestor, Charles Williams was the master *bloomer* beginning in 1698)
is not the *green-glass* variety, but rather looks more like *coral*,
with iron, charcoal and other elements mixed within.  We have this type
of slag not only at this site, but at a later site down the river where
a shipyard was established in the mid-18th century.  Iron from the
second bloomery was used to fit the 40-some vessels (plus other in the
shipbuilding town) until the mid-19th century.  The slag is usually
mixed with copious amount of charcoal-- we had a slag and charcoal
midden 6 feet deep on the shipyard site.
 
Cheers,
 
MB Williams
Dept. of Anthropology, UMass-Amherst