Mine Exploration Forum

Author	Grove Rake PDHMS meet 1989 (probably) (photo)
John Lawson Joined: 09/12/2010 Location: Castle Douglas Dumfries & Galloway View Profile View Posts View Personal Album View Personal Files View all Photos Send Private Message	Grove Rake PDHMS meet 1989 (probably) (photo) Posted: 13/11/2018 20:42:14 Reply \| Quote Hi This is almost certainly the famous marcasite vugh! To those of you who are not aware, Marcasite is similar in Chemical formulae to the more we’ll known Iron Pyrites. The main difference being marcasite is not very stable and in damp air will rot to nothing! Hence the interest at the time and the collecting foray! Under certain circumstances Marcasite can even be pyrophoric, ie it will burn when it meets the air. Tara Mine in Ireland had some problems with this mineral, of this nature. As far as I am aware this catching fire never happened at Grove Rake....replace this line with your message... Photograph: (click image to open full size image in new window) IP: 86.179.100.12
Jim MacPherson Joined: 02/09/2015 View Profile View Posts View Personal Album View Personal Files View all Photos Send Private Message	Grove Rake PDHMS meet 1989 (probably) (photo) Posted: 14/11/2018 10:16:13 Reply \| Quote Hi John, Thanks for that nugget, I'll add the info to the pic. I'll need to have a delve through the bits of Dad's mineral collection I kept (quite a lot went to Kilhope) and see if there is a piece lurking and it's also interesting to note that there is more than one way of spelling vug, which is even better in Scrabble Jim IP: 86.149.33.77
Peter Burgess Joined: 01/07/2008 Location: Merstham. Or is it Godstone ...... ? View Profile View Posts View Personal Album View Personal Files View all Photos Send Private Message	Grove Rake PDHMS meet 1989 (probably) (photo) Posted: 14/11/2018 14:02:26 Reply \| Quote That's fascinating. I only learnt this year that the so-called marcasite nodules found in the chalk may well be pyrite after all. I don't know how true this is. IP: 85.115.54.201
Minegeo Joined: 17/06/2008 Location: Ireland View Profile View Posts View Personal Album View Personal Files View all Photos Send Private Message	Grove Rake PDHMS meet 1989 (probably) (photo) Posted: 14/11/2018 22:13:17 Reply \| Quote Actually the marcasite at Tara was generally crystalline in crosscutting veins within the lower ore lenses and was not an issue for mining. The issue was in the Conglomerate Group Ore ("CGO") which contained massive but very fine grained framboidal metastable non-stoichiometric marcasite. Occasionally this sulphide would cause a pre-ignition blast whereby when a round was fired the cut would produce a dust cloud which would then ignite and cause the entire round to pre-ignite. The resultant explosion known as a sulphur-blast would cause extensive damage to mine infrastructure such as pipework and vent bags. Similar problems were encountered in the Upper G Zone and B Zone at Silvermines where very brassy metallic pyrite caused the occasional sulphur blast. The problem could be prevented by inserting lime capsules in the blast holes. IP: 207.189.0.3
Boy Engineer Joined: 20/06/2008 Location: Derby View Profile View Posts View Personal Album View Personal Files View all Photos Send Private Message	Grove Rake PDHMS meet 1989 (probably) (photo) Posted: 15/11/2018 17:08:59 Reply \| Quote fine grained framboidal metastable non-stoichiometric marcasite That's easy for you to say. IP: 83.216.139.158

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