G'day Nancy et al; If you want to check whether the fossil matrix
is limestone or not, simply place a single drop of acid on a place
that won't notice much and observe it through a magnifier. It will
only bubble if it is limestone or contains a carbonate.
Any acid will do even vinegar or fresh pickle. The only other
material could be silica and that won't bubble. Take care with the
drilling; you'll use a diamond drill with the job covered by water of
course, and you will raise and lower the drill very frequently. I
suggest that you should use a cone or ball burr to gently flare the
hole on both sides, then flare flare one end of the insertion tube
of such a length that it protrudes about one or two millimetres., set
it in with a good epoxy resin, then when hardened, flare the other
end of the tube. The flaring is extra work but will pay off as it
will avoid excessive wear on the holding ring or cord.
Cheers for now, John Burgess; @John_Burgess2 of Mapua, Nelson NZ