PRECIOUS AND SEMI-PRECIOUS STONES OF SPAIN

GALAN, E(1) and GARCIA GUINEA, J(2) (1) Dpto. de Geología. Facultad de Química. Universidad de Sevilla, Spain. (2) Museo Nacion~l de Ciencias Naturales. Paseo de la Castellana. Madrid-6, Spain.

ABSTRACT An investigation of the gemmological potential of Spain has shown that only four minerals,beryl, t topaz, quartz and olivine, have possibility for exploitation and commercialization. Deposits of other minerals, like andalusite, garnet,prehnite, variscite and apatite, could occasionally supply stones of gemmological interest. The majority of these deposits are found in the Iberian Massif (W Spain). Mineralotects are mainly pegmatites with greisen phenomena,contact metamorphism aureoles in pelitic rocks, skarns, hydrothermal ore veins emplaced in granite or pelitic series, supergene alteration of ore bodies and dunite enclaves in Recent basic rocks. The most significant data relating to the prin­ cipal deposits and the characteristics of the minerals of g emmological interst are summarized in this papero

INTRODUCTION

Spain is a country poor in gems. This is the most evident conclusion that one obtains from ~ the body of research completed during the past six years. In this period, the geological, mineralogical and petrological literature of Spain has been reviewed in detail in search of specific studies or any evidence of gem-minerals.

Proceedings oC Ihn 27th lnlcmalional Geológical on rcss. Volumc 15, pp. 355-375 NON-METALLI MINERA O RES © 1984 VNU Science Press Theses and monographs, private reports, and the geologic magazines have been examined. Museums and private and commercial mineral collections have been visited. Requests have been made to professional and amateur mineralogists asking for any information relating to Spanish mineral s with gemmological characteristics. An Occurrence Map describing the quality and quantity of gem-minerals in over JOO locations in Spain has been made from a file of data. More than 200 si tes were visited, and positive visits resulting in the Gemmological Map. Fifty of these locations were studied in detail. For this study of the gem occurrences, detailed maps were used, and materials (mineralizations and country rocks) were characterized by means of microscopy, X-ray diffraction, and chemical analysis. In addition, the minerals of greatest gemmological interest were the object of specific studies, including faceting and polishing tests, determinations of physical and crystal chemistry properties, and investigations of minerallotects and mineral resources. '*"",,------,.-- A clear idea of the real gemmological potential of Spain has been obtained from this study. The (~ CANARY 'r;;---: areas and mineral s most worthy of prospection and the methodology most suitable for future ~ 100 150 200 Km ! ~cc=ff ~ P investigation have been established. LI ~ ______\Y;J _ EXPLANA TlON

IBERIAN MASSIF(HESPERlC F\.ATEAUI ALPINE RANGES GENERAL OUTLOOK § CANTABAIAN 10N[ {lZLj ~:~~i5ió: ,~ )( ~~E FOAMED IIIIA INlY V77l7l PAlEQZOfC Of 'HE ",TALAN lLLL.LLJ R A H r,;, E D PAECA~8FlI"'N OF' THE HARCEA ANTlFORfoI _ PREIETlC lONE Mineral occurrences and g eologic location .0._ rA~~1~~~ .. ~i;:~NF- ~~:g~~)OHE ~ SUB8ETl C lOHE Fi~-"'';~ PAECAIIIIBAIAN OF TtfE "ou..o DE SAPO " ~ 8HIC (5. S.' ZOHE(A :HEVADO - ... " :. /' AJrlT,roflNe A~ FILA8fHOES COMPLEX) The minerals of possible gemmological interest El::1!fl ~~~Tt~~ ~1:ESR~:d , ~:E,.ATlON _ ..:AMPO DE GIBRALTAR COWPlEX that have been found in Spain thus far are the I::!;:;l PEOAOCHES BATHOLITH [BERIAN RANGE follo\"ing: ~ OSSA - NOflEHA rotE fA : PRfCAIlHlf«AHI ~ ATLAHTI C 0 0 1: : :3 YOLCAN fC fIIIATER IALS a) S~licates :Oli vine ( Oli) , Andalusite (And), A~ t:.UpT,(~~~I~T:'~~~T:~ A~ EA5TERN(A:FOLOED.8 : UHf'OLOEDI Kyani te (Ky) I Topaz (Top) I G-arnet (Gr) I FIGURE l. Tectonic Map cf the Iberian Peninsula, Zircon (Zr ), Idocrase (IdO ), Epidote (Epd), and Balearic and Canary Islands, and Cordierite (Cor), Tourmal ine (Tur) , Beryl Spanish Gem Materials (see text). (Be), Spodumene (Spd), Rhodonite (Rhn),

356 Pyroxmangite (Pyx), Quartz (Q), Felspars apatite, etc. 1n volcanic events are the most (Fel), Prehnite (Prh); noteworthy. Non-Si1icates:Diamond (Dm), Spine1 (Spl), Fluorite, topaz, idocra se, epidoie, garnet, b) malachite, amazonite, beryl, kyanite, etc., Corundum (Cdm), Flourite (Fl), Malachite- associated to metamorphic, volcanic and granitic Azurite (Mch-Az), Rhodochrosite (Rho), rocks have appeared in the axial zone of the Schee1ite (Sch), Variscite (Var), Turquoise Pyrenees. (Tq), Pseudomalachite (Pmch), Apatite (Apt) Pyroxmangite, sanidine, olivine, garnet and F1uorite is listed here in spite of its dubiou tourmaline in relation with volcanic and granitic gemmological interest to indicate the existence rocks and pegmatite veins in Ordovician and of marvellous crystals (blue, green, yellow, r e Cambrian materials stand out in the Catalan found in Asturias and Badajoz. But other perfec Range . and fine crystals have not been mentioned becau Th e Ca nary I s land s are espec iall y interesting they are not traditionally considered gem­ for 01ivin e b ecause of the vocanic origino minerals. These include: the pyrite cubes of Th o t h er tecto nic units ( t h e Iberian Range , Navajún (province of Logroño), the cobalto­ t h e Tertiary basins ) are of no gemm010gical calcite of Peramea (province of Lérida), the interest. beautiful sphalerites of the Peaks of Europe The percentage distribu tion o f the occurren ces (province of Santander), the famous Spanish gem-minerals in rel ation t o the genetical e nvi­ aragonites (green, violet), etc. ronm ent is t h e f ollowing : Intramagmatic 11%, Using the Tectonic Map of the Iberian Peninsul Veins ( of uncert a i n or i g in) 7 . 5% , Hydroth erma l (Julivert et al., 1974) as a basis, one can see 17 . 2% , Greisen 0. 9% , Pegmati t ic 15 .4%, Vo1canic the correspondence between the tectonic and 7 . 9% , Vo lcanic-sed i mentary 1.J%, Regional meta­ lithological characteristics of each of the mo r phism 17 . 2% . Contact me t a mo r phism J. 5% , Skarn ~eotectonic units and its "gemmological capacit 11%, Supergene 1. 8% , a nd Sedime n tary 5 .3%. (Fig.l). Mineral freguency and gem interest The Iberian Massif (the Hesperic Plateau) is, by a large margin, the unit of gratest mineral­ Mineral occ urrenc es of gernmo l og i cal interest gem wealth. The Southern-Portuguese zone is are distributed as f o110ws : oliv i ne 7% , kyanite interesting for its rhodonite, rhodochrosite, 2 . 7% , andalu s i te 4%, t o paz 6. 2& , garne 9 . 7% , j asp er a nd mal a chite-azur i te ; t h e Ossa-Mo rena zircon J. 7% , idocrase 4.4%, epidote 5 .3%, beryl z one f or t opa z, q u art z , ber yl, epidote , garnet, 8 . 8% , t our ma line 1. 8% , spodumene 0 .45% , r hodonite etc.; t h e Pedroches bat holith for turquo ise , 1 . 3%, q u artz 14 .1%, feld spar 0.45% , prehnite ma l ach ite , p seudoma l a chite , etc .; t h e Central ­ 2 . 2% , diamo nd 0.45% , spine l J. 5% , c 01'1 .ndum 3%, Iberian z o n e f or t opaz , beryl, quar tz , andalusi1 f l u o rite 0. 9% , ma1 a chi t e - a zurite 7 . 9% , s c h ~elite spodumene, variscite, apatite, etc.; and the 2 .7%, v arisc i te 0. 9% , t ur quoise 3. 5% , apatite Western-Asturian-Leonese zone for andalusite. 4%, p seudoma1achite 0. 9% . Among t h e Alpi n e r a nges, t h e Betic Range aboun Logic a l1y , t h e percen tages o f mineral s a r e not in gem material s ( esp ecial y i n t h e Betic S . S . rel ated t o t h eir petrographic abundance ; gem­ zone ). Garnet , andalu site , quartz , t ourmali ne , mo 10g i ca1 cri teria were t h e basis f o r se1 ection . kyanite i n metamorph ic material s ; oliv ine , Most of t h e cata10g u e d ccurrenc s are small , spin e l, diamonct (? ) in ul trabasic roc!es ; and making mineral extraction difficu1t. More than agate . garnet , co dieri te , spinel, olivin , 50% of the cited minerals occur as minor petro­ ::¡ graphic components, or occur abundantly but very '":::> 1-z scattered. '"> '" On the other hand, the gemmological quality of ~ the found m~nerals is doubtful in more than 80% :::> '"u. of the cases (for diverse reasons: concentration, size, coloration, fractures, impur it~es, etc.), which is evidence of Spain's gemmological pover­ ty. Only very few of the deposits can be mined. The most interesting minerals are: olivine,topaz, N '" ... '" beryl and quartz, and the follovTing may have secondary gemmological value: andalusite, garnet, epidote, rhodonite, prehnite, fluorite,variscite, turquoise, pseudomalachite and apatite. (j ~ 00 Q)

c;;s. N rona) ha.ve gemmological interest (Fig.2). Among ro o. these, the Lanzarote stand out for their olive­ o E-t green colour, transparency and abundance. Size ranges from 0.1 to 1 cm and they are suitable .,-' , 'Oe for cutting. All are forsterite (Fo 80-90), and ro they have not been thus faro ~ ... ! q:{ " ~ Q) r \ 1- e Topaz ~ ·rl , . ? Fourteen deposits of topaz were selected for 'rl r-I study. Topazes appear as accessories in granite o and in beach sands. As a particular case, topaz has been found in quartzite beds interbedded in C\l gneisses (up to 20% topaz). The principal topaz ¡:il p:: deposits are those of Valle de la Serena and Mé­ :=> rida (province of Badajoz) and the Lovios deposi 0 H (province of Orense) (Fig.2). The topaz occurs ¡z.. in pegmatitic dikes altered by pneumatolytic processes (greisen) associated to apical borders of granitic batholiths. The topazes of Valle de la Serena are crystals up to 7cm 1n size, green-blue 1n colour, without TABLE 1 fractures, and rich in fluor (Garc{a Guinea et al., 1978). The topazes of Mérida are smaller TOPAZ: PHYSICAL CHARACTERISTICS AND FORMVLAS than those of Valle de la Serena (up to 4cm), VALLE DE LA SERENA MERIDA of varied colour (colourless, yellow, green), without fractures, and very clean and transparent Specif'ic 3.56 (Garcia Guinea, 1981a) (Table 1). But doubtless gravity 3.55 the most interest samples are 1n the recently no<: ,n.p , 1. 617; 1,618 1. 612; 1. 615 discovered deposit in Lovios 1n the Sierra del na- 1.625 1.620 Jurés, where their size can reach 15cm. 6['° These deposits are worthy of interest, but 2Vr their exploitation depends on the accompany1ng Colour Greeish-blue Blue, green metallic mineralizations. So fa, Spanish topaz yellow,colour has not been mined. less - Beryl Absent Absent Fractures Probably the principal mineral of gemmological Transparency Very high Very high interest 1n Spain 1S beryl (Galán and García Guinea, 1980; García Guinea, 1981b). The most Lapidation important deposits are located 1n the Iberian Very good Very good tests Massif, where geological conditions have favoured Unit cell a o = 4. 6551 (~3 ) A a o =4 . 648 ( + 2 JA the emplacement of pegmatites, the chief beryl­ dimensions bo = 8. 8062 (:t. 6) JI.. b a =8 . 79 5 ( ~ 1 ) ~ bearing rock. This plateau 1S an area formed by Ca = 8. 3953 ( :t.5 ) JI.. Ce) = 8 . 3 9 1 ( :t.1 ) 11 Hercynian and Prehercynian materials where suf­ 2+ ficiently deep erosion has resulted 1n the un­ Formula (A18.02Feo.005 (A1 8 . 016) Mg cover1ng of peribatholithic pegmatite bodies CaO . 004 o. 004) of a real entity. (F7.380HO.60) 39 occurrences have been selected, but only those emplaced near Pereña (province of Sala­ (Si3.96AIO.04)016 manca) and Sierra del Jurés (province of Orense) may have gem-quality. The following occurrences might also be studied further because of evidencE of great abundance of beryls: S-SW Pontevedra, the Lugo area, Sierra de Guadarrama (provinces Madrid and Avila), Plasencia-Montánchez-Mérida (region of Extremadura) and Sierra Albarrana (province of Córdoba) (Fig.3). The Sierra de Jurés beryls are in granite peg­ matites (quartz,K-felspar, Na-plagioclase, W, Sn and Mo ores, and other metallic minerals of Fe, Cu, Bi and Zn), and were formed during a very early stage. Peg~atite veins reach 2Km in length and 2m in thick. Hexagonal crystals of beryls up to l5cm in length and 2cm in diameter, ~ are grass-green and semi-transparent or dark ~ :lE w blue and opaque. Colour can be attributed to Ir 1- i~on. I:l the presence of vanadium and ~ z ~ cn ... w Ir m w a: ~ w , transparent beryls occur with corrosion channels U W -' \5 = ... a: ... :I: t!> z a: W , w w ... u w and bertrandite (hydrothermal alteration). They W ::::> ¡¡; -' a: "- ¡¡; en -' iii "- t!> cn "- I~ are grass-green in colour. From them, perfectly I ~ • + I u transparent and beautiful gems (aquamarines), '" '" '" '" []... ? ¡ more than 2cm in size, can be obtained. ~ tJ From their chemical analyses and on the basis of the crystal chemistry interpretation made by Schaller et al. (1962) for beryls, the formulas recorded in Table rr can be proposed. Physical properties have been determined and lapidation and polishing tests have been carried out (Table rr). Both two beryls can be considere 4-' ti) common with discreet gem possibilities, but so E amethyst of Pedroches), or Pb-Zn (amethyst of C""\

Portman), and in sedimentary enviro~ments (agate ~ o:: o f Palmaces d Jadraque, authigenic idiomorphic ;:::J rock crystal of Colunga, Verbis, Cabrales, etc.) Ó H (Fig.4). r:...

365

1(,4 (ñ' TABLE 11 s: .. :J'" BERYL: PHYSICAL CHARACTERISTICS AND FORMULAS '" ID '" 2.7 2.7 -;¡ ~ z W z ~ Co1our Grass-green Pa1e o ID Q. :;'" ~ ~::!; N 3 en J O :; d W .... ~3 ~ ~ 1f u :r:: W Fractures Scarce Absent

N +> '" " ... lI) Corrosion Absent Many hexagonal '" mI] "'e Ol "e H channe1s I/c ...Ne Ol +> fi11eé -. ¡:: Inc1usions None Channe1s H with pyro1usitE ~ & E bertrandite Ol kao1inite c..J C¡....¡ Transparency High Very high w .... o u 1: ~ Lapidation z Unit ce11 Ol "M dimensions Not determined a o ==9.219(+1)Á H ro co ==9 . 182 ( +"3 ) A w en t:: :> ~ . Formula (Na,K,Ca)0.21 (Na,Ca)0.076 ou'" 'O a: ¡:: ~ ro (Be,A1)~ 67 (Be,A1)~ 62 (~( 3' 2+ 3' 2+ · l~r~ · ! ¡1J~ : ¡ t ~ N (1¡,Fe ,Fe , (A1,Fe ,Fe , '. ~ ", t: v +> H V ,Mg,Pb,Zn, Mg,Pb,Zn,Zr, } '¡;, ¡ ro l\ ; Zr,w)4 [ .~ . ;::l w~4 'J O' 8i11.90036 81. ' : . 12°36 .:j' rz::¡ p:: / ~ / c..J H ~

1(,7 1flfl Cl The pink quartz of Oliva de Plasencia and the agates of Palmaces de Jadraque stand out for o« U o ~..., .0« < ir ~ ~ a: o« o > U their abundance and gem-quality. They have given ::> o« ...J ~ ::> lIi '" Zl a: ...... , ir (/) iS o« ...J ~ ~ lIi beautiful and high quality pieces after polish­ ~ o iii a: ...... '"a: '"lIi ...J :'3 .. '"::> o o ...J ...J ~ mII! N o« '".... ing and faceting. Exploitation is adviseable. o« ~ ~ o« o« ...J ::> ~ O S ~ ~ ~ o« ...J .., ...J- .... I!!- -' o« m a: Z 0«0« '" -N i z The other previously mentioned varieties of !:! ~ ~ O o« ,,-'" X :Z:o ... ~ :'3'" .., -' O U u.., ;; '"~ ~ O ...... lIi o« ...J quartz could be extracted secondarily when the z '"~ O I!! 15 ...o 00« -' ~<3 ... Q. .... 15_ 15 ",t! .. o Q '" l5 Z u accompanying minerals are mined. ~- ~ .... I ~! ,;: .... z ~ cf ....'" '"...... '" -(/) O ir o« ~ 0-, ~ z z z uo« o 80« '"t: o« ~S :z: x !!!> ::> ::>e Q. ~ z :z: .... '" ~ a:'" ",a: u z o« "-m Xx a: a: 0«::> u K' "-lIi .. '" '" MISCELLANEOUS (Fig.5) N '" .. lO Garnets El Q) (J) Spanish garnets have little gemmological value. Garnets are found in skarns, schists, and in .c: (fJ sedimentary and volcanic rocks. The garnets of 'M ¡:: El Hoyazo, Nijar (province of Almería) are impor ro tant because of their abundance and favourable - p., (J) exploitation conditions. They are red almandines reaching lcm. Some of them could be cut. H Q) ..c: Epidote 4-' o Skarns epidotes are very abundant in SW Spain. Those of Jerez de los Caballeros (province of Badajoz) occur as large green and translucent fibers with sorne cu possibilities. Rhodonite This mineral appears associated to pyrolusíte deposits en the province of Huelva. The better specimens are in Valverde del Camino, but the pink colour is not very intense. Rhodochrosite is sometimes found, but it appears without gem 369 • These variscites can be cut, but their gem value is only moderate because of the softness of the interest. mineral. Pyroxmangite, SiO (Mn,Fe), a mineral similar to The Zamora variscite has historical interest; rhodonite, has bee~ found in Montroig (province it was confused with emerald by the Arabs. This of Tarragona). Cut and polished pieces of various confusion resulted in the provin~e's being named shades of pink are beginning to be commercial­ "Zamorat", meaning emerald. ized. Turguoise Prehnite Spanish turquoise appears ln copper velns PrehLite is frequently a hydrothermal product emplaced in schists and in granites, but none of dolerite alteration. The most important are of the samples studied so far have gem interest those of Caravaca (province of Murcia) (García because of their small size and lack of coloring, Cervigón et al., 1976) and Conil (province of which is due to their intimate association with Cadiz) . amblygonite (of pale blue tone). The mineral also appears by hydrothermal alter­ Pseudomalachite ation in pegmatites, as in the case of La Cabre­ ra (province of Madrid) (García Guinea et al., Found in Andujar (province of Jaen) and in 1982) . . Oliva de Mérida (province of Badajoz), it is The Caravaca prehnite is light green, appearlng associated to deposits ofcopper and uranium in fibrous aggregates up to l5cm in legth. Its phosphates and formed by supergenic processes. gemmological characteristics.are goo~, although The pseudomalachite may have sorne gem value in it is rather opaque. The Conll prehnlte lS forming "reconstructed stones", because of its similar but more yellow in colour. intense green colour. The La Cabrera prehnite is of relative ge~ . Reconstructed stones made with plastic and interest because of its physical characterlstlcs 10% finely pulverized pseudomalachite have a and size (up to 2cm) and cut easiness aptitude. jade-like appearance and can be cut (Galán and García Guinea, 1982). Fluorite Apatite Spain is very rich in f~uor~te. The Asturi~s fluorite stands out for ltS lntense coloratlon This mineral lS common in Spain, but only those (violet, green, yellow), its cleanness and of Jumilla (province of Murcia), which are transparency, its size,and its lack of fractures. associated to alkaline volcanic rocks, have The intense red and green fluorites of Valle de gemm~iogical interest (Rodriguez Gallego and la Serena are also very beautiful. However,other García Cervigón, 1970). These apatites can be than these deposits, Spanish fluorite has little as long as several centimeters. Pale yellow and gem interest because of its softness and tend­ green in colour, they are totally transparento ency to exfoliate. Containing few fractures they can be cut or set ln rough. Although somewhat soft, the gem value Variscite of t~is apatite is obvious. The Palazuelo de las Cuevas (province of Za­ mora) variscites (Arribas et al., 1971) are epigenetic nodules or veinlets formed ~n hyper­ aluminic shales by means of phosphus-rlch waters. 371 •

G~rci~ G~lnea,J. ~~~~~b). LeS bery~s espagr d un lnteret gemmologique. Revue de Gemmol{ a.f.g. 66,2 TABLE 111 García G~inea,J.; Belli~o,F. & Galán,E. (15 PRINCIPAL MINERALS MINERALOTECTS AND LOCALITIES FOR RE L~ prehn~ta ~e La.Cabr;ra (Mad~id). CaractE tlcas,.geneS1S,e lnteres gemologico. Bol. E Esp. Mlneralogla 5, 29-41 . MINERAL LOCALITY MINERALOTECT Dunitic enclaves Julivert,M. ;Fontboté,J.M. ;Ribeiro,A. & Cond Olivine Lanzarote Fuerteventura in basalts (1974). Mapa Tectónico de la Peninsula Ibér Canet de Adri y Ba~eares. I.G.M.E. Ministerio de Industri Madrld. And a lusite Boal Contact metamor ­ phism in peli t es Rodri~uez ~ a llego,~ .. & García Cervigón,A. ( Estudl0 c~lstalograflcO y mineralógico de 1 Topaz Valle Serena Pegmatites esparragulna de Jumilla (Murcia). Cuadernos Mérida Geol. w 1,27-30 -...¡ Lovios SChaller,W.T.;Steve ns,R.T. & Jahns,R.H. (19 N Beryl Pere ñ a Pegmatites An unusua l bery l from Arizona Am Mineral Sierra Jurés 672-699 ". Pink quartz Oliva Plasencia Veins ln granodiorite Citrinej Smoky Villasbuenas Veins ln granodiorite quartz Amethist Pedroches Veins ln granite Portman-La Unión Veins ln volca nic rocks Agate Palma ces de Andesitic volca n6- __ J,...... :J ...... , .... ,..." r.\ _ Jasper Zaló'.mea la Real Mn-ore veins in s ~ hist~ Valverde Camino Prehnite Carava ca; Conil Veins in dolerites La Cabrera Pegmatites Variscite Palazuelos de Nodules or v e inlets in las Cuevas hyperaluminic sha les Ap a tite Jumilla Alkaline volcanic rocks

G.I . = Gem Interest on the basis of 10 points.

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