Geology and Mineral Resources of Paraguay A Reconnaissance

MINERAL RESOURCES 95of lead and silver, patrinite, antimonite, and six unidentifiedcopper minerals. Some of these mineralnames suggest the possibility that they representspecimens that originated in Bolivia or Peru ratherthan Paraguay.FUTURE OF THE MINERAL INDUSTRYGENERAL STATEMENTAvailable facts indicate that Paraguay is very poor inmineral resources except for certain nonmetallic materials,such as clay, limestone, talc, sand, and variouskinds of building and ornamental stones. It is possiblethat further exploration will serve to uncover otherresources. Even if such hopes should prove to beill-founded, however, there is every reason to believethat profitable local industries could be established thatwould provide some or all of the nation's requirementsfor certain commodities and would conserve some of itsforeign exchange.The author's pessimistic conclusion as to Paraguay'srelative poverty in minerals is not reached lightly norwithout reluctance. Nor is it based entirely on theresults of the present 6-month reconnaissance that wasinadequate to examine more than a small fraction ofthe mineral possibilities. Instead, it is based in parton history and in part on generalized knowledge ofthe geology of the country.For nearly four and a half centuries, many men,some highly skilled in their profession, have soughtmineral wealth in Paraguay. It is easy to believe thatall of them may have missed the obscure or the deeplycovered deposit, but almost inconceivable that allwould have failed to discover obvious deposits thatwould be most easily found and developed. The factthat they have not done so is in itself strong presumptiveevidence that easily discovered deposits do notexist.So far as the geology is now known, the Precambrianrocks offer the best chances of discovering depositsof metallic minerals. Unfortunately, these rocks arecovered in most places by barren sedimentary rocks,or by swamps and many of the exposures that do existare remotely situated and difficult to explore. Noneof the younger igneous rocks appear to be of the kindswith which ore-bearing solutions are usually associated.As a result, neither they nor the surrounding sedimentaryrocks, none having been fractured or metamorphosedenough to make them promising receptaclesfor ore deposits, seem to be of much promise.These conclusions are at variance with widespreadpopular beliefs within the country that are based inpart on the inevitable enlargement of legends withtime, and in part on failure to distinguish betweenmineral occurrences and mineral resources. The beliefin existence of gold and silver resources, for example,seems to be based entirely on stories that theearly Jesuits found and produced fabulous quantities ofthese metals. Actually, there are no authentic recordsof such production and no assay reports or other proofthat paying quantities of gold have been found sincethe time of the Jesuits. Again, the almost universallyheld belief that Paraguay is rich in iron is based onthe well-known fact that local mines and furnacesproduced all the iron needed in Paraguay's epic struggleagainst three powerful adversaries Argentina, Brazil,and Uruguay during the War of the Triple Alliance.As a matter of fact, Paraguay does possess rich irondeposits, but there are many reasons, geologic andotherwise, for believing that they are far too small,individually and collectively, to form the basis of anexport business. Too, many beliefs in mineral richesare based on small specimens, with little or no proofthat they represent workable quantities of ore. Thus,though manganese and copper are undeniably presentin several places, there is no evidence known to theauthor that bodies of commercially workable size andgrade have ever been discovered or developed. Similarly,though specimens of sheet mica can be seen inmany private and public collections, none of those seenwere of much more than scrap quality; moreover thereis little more than hearsay evidence that large depositsof mica, regardless of grade, have been discovered.Part of the author's pessimism is based on the merefact that most specimens of metallic and other mineralsor ores seen are far below commercial standards. It isonly human nature to select better-than-averagematerial for specimens; if all specimens of such easilyrecognized materials as gold, mica, manganese, andcopper ore are mediocre in quality, it is difficult tobelieve that the deposits from which they came aremuch, if any, better. This reasoning does not apply, ofcourse, to the less-easily recognized minerals, such as theores of tin and tungsten, nor to such things as petroleumthat can only be discovered by extensive undergroundexploration.SUGGESTIONS FOB PROSPECTINGPresent knowledge strongly indicates that Paraguayis relatively poor in mineral resources. Details of thegeology are but imperfectly known, however, and manyparts of the country are so inaccessible as to haveescaped very careful search for minerals. Furtherexploration, therefore, seems justified.Many suggestions for prospecting are offered on precedingpages in descriptions of individual commodities.These suggestions are only summarized here.In searching for deposits of the metallic minerals,and many of the nonmetallic ones, it is always well to