The metallurgical usage of the word 'bronze' refers to any metal alloy
that has copper as its principal element. Arsenic, tin, zinc, manganese and
aluminum are commonly combined with copper to make 'bronze'.
For most of us, though, 'bronze' means a copper-tin alloy. Copper-zinc is
is brass.
When you read about bronze in the literature, you frequently
don't quite know what the author is talking about; and sometimes, I think
even the author doesn't know what he's talking about. Arsenical copper
is copper with a (usually naturally occurring) trace of arsenic; this makes for
a superior metal, much better than pure copper, but not hard like 'true'
copper-tin bronze.
The Kuro-Araxes culture in the Caucusus (3500 on down) was remarkable for
its bronze, but I don't really know what kind of bronze this was. The Ezero
culture in Bulgaria (3200 on down) is usually stated to be the first European
bronze age site, but again, I don't know what kind of bronze they dealt
with. EIEC tells me copper mines were known in the Middle Danube and in
Bulgaria from the 5th millennium on down. Copper deposits in
the southern Ural Mountains seem to have been utilized by the
Yamna[ya] culture. The Afanasevo culture, 3500 on down (imputed to be
proto-Tocharian) was way out the upper Yenisey, and was also known for
its copper and bronze.
EIEC (Martin Huld), under "Iron" notes the various words used for iron.
"the irregular relationship of the consonants in the putative equation of
Lith sidabras and OHG sintar (defying Grimm's Law) and the anomalous nasal of
the Germanic form indicate a loan source in Balto-Slavic, Germanic, or both.
These loans may suggest than an active (non-Indo-European?) metallurgical
tradition survived in central Europe until the Iron Age."
I have my own unproveable speculation that the 'elves' (*albh) were
non-IE-speaking metal-workers. Certainly, knowledge of metal came from
one or more different language families.
Mark.