Assayers in the UK do not use Borax for fire assays, & this includes the
Assay Offices. The company I run does up to 50 fire assays a day.
The fire assay technique does not use a flux, because Lead is used instead.
The technique dates back to at least the Romans.
I suspect your talking about the preparation of samples from ores prior to
the final fire assay.
Ian
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Sent: 03 April 2000 21:35
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Subject: RE: Borax
To correct Ian:
Borax was routinely used in the fire assay of gold and silver between 1973
and
1989 when I worked with Capper Pass. we conducted something like 200
commercial assays a month using flux containing borax. During that time I
have
visited assay houses and other smelters some of whom have incorporated borax
into fluxes. It was a matter of established practice so I don't know the
specific reason but would guess that it gave a cleaner pouring slag when
dealing
with samples from a wide variety of sources and where you need a much more
versatile flux that lead silicate.
Richard
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