new to Ireland. Introduction. Muckl-oss ..... A search of Irish and British museum collections failed to yield any ... Jukes and Du Noyer (1859), however, regarded ...
UNUSUAL SUPERGENE MINERAIJS AT MUCKKOSS MINE, KILLARNEY, CO. KERRY S. MORETON, P. DAVIDSON. D.I. GREEN AND G. RYRACK
Abstract Copper, iron, lead. zinc. cobalt, silver and arsenic mineralisation occurs in Carboniferous litiiestone at the disused Muckross mine. Co. Kerry. The primary ores include sulphides (chalcopyrite, galena, pyrite and sphalerite). sulpharsenides (alioclasite, arsenopyrite and tennantite). native silver and skutterudite in calcite gangue. Post-rnining oxidation in the f nine waste has given rise to secondary carbonates (aragonite, hydrozincite and inonohydrocalcitej, sulphates (brocharrtite. devilline. gypsum, hydronium jarosite. linarite and posnjackite) and arsenates (erythrite, lavendulan, olivenite, mimetite, parasymplesite, phaunouxite, rauenthalite and smolyaninovite). Alloclasite, monohydrocalcite and the last four arsenates are new to Ireland.
Introduction Muckl-oss mine (National Grid reference V948858) is a disused copper mine in lower Carboniferous limestone on the northern shore of M~lckrossLake, in the grounds of Muckross House, Killarney National Park. Co. Kerry. The first recorded period of working was from 1749 t a 1754. during which some f30,000worth of ore was raised (Wright 1819). worth around l R f l O m i l l i o ~in~ today's values (Larner 19%)). There wer-e two adjacent wot-kings along the lake shore, w l ~ i c lare ~ describecl i n det~rilby Weaver ( 1825a: 1838). who said that the western tvorking was the larger and riches. It reached a depth of about 30 fathoms (55in) and had a 1;ttcl-al extent of 27 fatholns (501-n). Several attempts at reworking the tieposit were made between 1785 and 1818. I t was
during one of these attempts. in 1794, that cobalt was identified in the waste fro111 the western working by mining engineer Rudolf Erich Raspe (GI-iffith 1824). better kno~vnas the author of the Baron Munchausen stories. The earlier miners had failed to recognise the cobalt and discarded i t as worthless. Most seems to have bee11 tipped into the lake (Kinahan 1887) or used i n road-making (Griffith 1824), altliough some 20 tons ( 1 9.6 tonnes) were recovered from the waste by an unk~iown'adventurer' (Wright 18 19). The ores were descr-ibed as 'grey & yello\v copper ores', pyrite and 'arse~iicalcobalt' with calcite in a rouehly east-west bed of 'blackishprey slate-clay' in limestone (Weri\~erI 825a). 'There seems to haw been some de\-elopment of an oxidised zone carrying secondary mineralfs. as the oldest prthlished accorrnt
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Mor-eton-Ir:
J. E(1:crrrhSci. (1998/9)
(Smith 1756. 125, 408-1 0)) I-ecords native copper and ~nalachitefrom the mine. At the mine site todtly, the visible remains consist of some fenced-off depressions (probably infilled shafts) and a small area of' mine spoil on the lake shore. These are niostly associated with the larger, westerr) working. Most of the spoil is poorly mineralised, but a snitlll area, occupying the western working itself (a stope to surface now almost completely infilled) and consisting of only a few cubic metres of rubble, was found to be particularly rich in metallic ores and a large variety of secondary minerals. This area provided most of the material described Iiere.
EDX analysis indicateii the prcsence of mi~lor S and CI, in addition l o sil\:er. o11sotile parts of' tlie specimens. but these coultl not be I-elaced to any visible phase n~idpl.c>btrblyrepresent rece~lt superficial allel-ation of tlie primary silver. The gangue of all the metallic ores is n~assive. white calcite with very ~ilinor,\:cry thin (< 0.211im) films oi'quartz. A more detailed accotlnt of' the prinlary minerals from Muckross {nine, and the nearby Ross Island mine, is currently in preparation by Dr Rob Ixer (pers. conin?.).
Seconck~rj~ lizi~zei-01.7 Post-niining oxidation within the waste has given rise to a wide variety of secondary u Mineralogy mine]-als. some of which are extreniely r;lre. tinless otherwise stated, the secondary This section lists and describes the n~inerals minerals were all found as coatings anti found at Muckross mine. X-ray diffraction encrustations on lun~psof massive sulphide/ (XRD), at the Royal M ~ i s e u ~ofn Scotlanci and sulpharsenide ores. Manchester Museum. was the principal method of identification used in this study. This was Ar~lgor?ire CnCO,. Ari~gonite occurs as ttiin complemented by infra-red spectroniet~-y(IR); (c.0.1-0.25mni). white to pale blue. by Dr G. Ryback, X-ray fluorescence analysis niamillated crusts, with individual spheroids of (Royal Museum of Scotland). energy upto I mni. It was identified by XR13. dispersive X-ray analysis on a scanning Hroc.lztriztire Cri,SO,(ON),,. A bright-green, electron niicritscopc (SEIV EDX. at ~nicrocrystalline crust with occasional poorly Manchester Museum) and classical wet formed crystals up to 0.2m111 long on lin~estone cheniistry. was identified by IR as brochantitc. PI-~IIICII?. i~~ii~er~~li.~~rrioi~ The pri~nary ore consists mostly of f'inegrained. banded chalcopyrite, tennantite. pyrite, at.senopyrite, galena and sphalerite. Most of the cobalt ore seems to h a w oxidised in the mine spoil and very few specimens containing unaltered cobalt arsenides were collected. In ~nost cases tlie cobalt arsenides \\.ere completely altered to erythrite a n d smolyaninovite. Those that were not were identified by XRI> as alloclasite i ~ n d skutterudite, 170th occu~-I-ingas fine-grained disseniinations i n calcite in association uith othe~.sulpliidcs and sulpharseni(tcs. Three specimens of natil-e sil\rer. as malleable, tarnisheti leafy or irregular grains t ~ p to 1.5nim across in calcite acco~npaniedby the other pr-imary ores :ibove. were found. SEM
Dc~lilline CnCi(,(SO,),(OH),.3H,O. DeLlilline (XRD identification) occurs as pale blue to greenish; pearly encrustations and as minute (c. O.51nmj.poorly formed. lath-like crystals on chalcopyrite. *
Ei-xthr-ite Co,(i\.vO,),.81-1.0. El-ytllrite is common as vivid pink to crimson encrustations up to 5mm thick. These ;\re c o ~ i ~ m o n l y rnaniillatctl and mint~tely cl.ystalline. specimens arc very pale pirtii: XRD confil-ms even these to bc ergthrite. SUiM El>X analysis of five specimens f;~iled to ctetcct signif'icant levels of othe~-elemcnts that rni~litaccount for the pale colour (e.g. Ni. Mg. Zn). G'j*p.rrrrlr C'(rSO:.2N,O. Gypsum occul-s as colourless. white 01.greyish ci.ystals up to 5mm long and as drusy. crystalline encrustations. I t was identified by XIID.
lr. J. Ecrrrh Sci. ( 1 998/9)-Moreton
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Nyclr-or~irriiz jai.o.sit~ ( N , O ) F e , ( S O , ) I ( O H ) , . USOWII. powdery masses up to 6cm across are common in the mine dump. Some have been identified by a co~nbi~iatio~i of XRD and SEM IZDX analysis as hydronium jarosite.
detcrminatroit of tlie posit~on\ot the d,,,, anci d,,, 11nes on the X-ray powdei diffr,tct~o~l photograph
k1\~ei7tlulnnNLIC~IC~~(A.SO,),CI.~H,O. Lavendulaii occurs as blue. ma~iiillatedcrusts cornposed of minute ( c . 0. l mm), thin, lath-like crystals identified by XRD and SEM EDX.
Xalieirthalit~ Cci,(AsO,),. IOHIO. liaue~ithalite occurs as chalky, white, spheroidal rnasses I-1.5nim across occurring individually or in groups of up to a dozen. It is visually alniost indistinguisliable froin monohydrocalcite, witli which it is comtnoniy associated. It also occtlrs as sprays of colourless, acicular crysfals up to 4mm long. Identification was by XRD.
l3onijcrckitc Ci(,SO,,(OH),.HIO. 1R idetltified minute (ir,\ Londor~5. 595-8. 37-8. STEf'HEN MORETON. 33 h4;il-ina Avenue. GI-catSankcy. \Varrington, Cheshire MJ.A.i If-IY, Engl:ind. IIK. E-mail: ste[lhen.niorcto~~@cri)\fii:I~i,c~~~~~
DAVID I. GREEN. Depal-trticntof Mineralogy. Mnnchesrer hfuseu~n. lini\:crsity of Mancl~ester, Oxford Road, Mancirester M I3 9PL.. Engi~ind. UK.
I'CTEIZ DAVIDSON. 1)cparimetlt of Geology. lic~yalMnseun~ofScot1;ind. Chanibers Street. Edinl~urghEl31 I JF, Scotland.
GEORGk RYUACK 42 Bell Ro'id S~ttrnpbourne, Kent ME10 4EB, England,
UK.
UK
