FMF - Friends of Minerals Forum, discussion and message board

[jfc035]

Hi
I recently purchased this bournonite specimen; it is from the Charles Noll collection (so likely a specimen he acquired in between 1940-70) and said to be from Harz. I was doubtful of the Harz origin before purchasing it (it is not from Neudorf), but curious, as it does not look like bournonite from South America or Romania (mostly because of the pseudomorphs mentioned above).
Actually, in many places the quartz is replacing thin platy crystals of what were most likely barite. So this reminds to Herodsfoot where those quartz a. barite pseudomorphs are ubiquitous. Yet the bournonite crystals does not figure the "usual" cogwheel twinning often seen at this UK mine. However, all bournonite from Herodsfoot do not necessarily show such cyclic twinning....
Apart from drusy quartz and bournonite, the specimen contains a tiny bit of chalcopyrite (covering some of the bournonite crystals)
so, has anyone a clue if this could be indeed a Herodsfoot specimen, or rather from another locality(in Harz??)
thanks
Jean-François

[Andreas Gerstenberg]

Hi,

this is, in my opinion, a Herodsfoot piece. These druzy epimorphs are quite typical. You never see that on Neudorf specimens (so you don´t at any Harz locality). I´ve seen a similar one labelled as "Bräunsdorf, Saxony". That was an English one as well...

Best regards
Andreas

[jfc035]

Thanks Andreas
I just received also a feedback from Steve Rust who votes for Herodsfoot as well.
Best regards
jf