Bark paper

I'm trying to identify the support material on a manuscript brought into
the lab recently.  It's from Alaska, turn of the century, smaller than
8 x 11", medium pinkish-brown in color, with purplish pits ranging from
4 - 14 mm.  Under the microscope there are no signs of fibers, but it
looks cellulosic rather than skin-like. With transmitted light you can
see layers of irregular torn strips and the sheet varies in thickness
from bond weight to 10 point card thickness.  It's very smooth and a
little lighter on one surface than the other.  Maybe it's some kind of
bark.  Does anyone have any ideas about what it might be or what tests I
might perform to identify it? Thanks.

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                  Conservation DistList Instance 4:32
               Distributed: Wednesday, December 12, 1990
                        Message Id: cdl-4-32-004
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