Geology and Mineral Resources of Paraguay A Reconnaissance

MINERAL RESOURCES 97These range from white to red in color and many ofthem form very attractive stone for flagstone walks,walls, and exterior facing for buildings. Large quantitiesof broken stone, mostly basalt or other darkcoloredigneous rocks, are used for street paving, forrough wall construction, and for foundations of allkinds. All these materials are quarried by very simplemethods and little or no attempt is made to improvetheir natural appearance by cutting, polishing, or otherdressing.In addition to the rough building stones mentionedabove, it should be possible to produce many kinds ofmarble from the large deposits that outcrop along theRio Paraguay from the mouth of the Rio Apa southwardto San Salvador. These rocks range from uniformwhite or gray through mottled and striped rocks ofvarious shades to what should be an excellent verdantique serpentine marble. Crushed and powderedmarble of a high degree of chemical purity could beproduced as a natural byproduct of a small marbleindustry, or could be easily produced by the Vallemicement plant, which already has all the requisite crushingand grinding equipment. The possibility of usingthe waste products from the Vallemi plant for agriculturallimestone is discussed on page 87.Several distinct types of light-colored granite withvery attractive texture, all durable and suitable forornamental stones, exist in the general vicinity ofCaapucii and Quyquyo, and probably elsewhere. Thereis also some strikingly beautiful and extremely toughblack "granite" (alkalic shonkinite) at Mbocayaty.The establishment of an ornamental stone industrywould require, in addition to technical knowledge thatis probably not now available in the country, a considerableinvestment in equipment for quarrying, cutting,and polishing the stone, Once the industry wereestablished, however, about the only continuous importrequirements would be small amounts of explosives forquarrying and abrasives and acids for cutting andpolishing.GLASSWAREExcept for three plants that produce common bottlesand jugs, virtually all of Paraguay's requirements forglass are imported. This is a particularly unfortunatesituation because, with such a fragile and bulky commodity,transportation charges necessarily form a highproportion of the final costs. Paraguay could probablynot compete successfully at this time with foreign producersof plate glass or the finer grades of domesticglassware, but there is no reason why it could not producemost of its requirements of the common grades ofglass for commercial and domestic use, such as heavywater glasses, bottles, jars, and other containers. Acheap local source of glass jars would remove one of thechief obstacles in the way of preserving more fruits andother foods for domestic use and even for export, thanis done at present. It would also provide a constantsource of supply for the local bottling industry, whichis now forced to shut down from time to time becauseof a lack of containers.Silica sand is the main ingredient of all glass. Sandand sandstone are abundant in most parts of Paraguay.Much of it is of excellent quality and purity for glassmaking,although most of the sand contains enoughiron to tint the glass green or yellow. This difficultycan be avoided by careful selection of iron-free sandor by the addition of small quantities of manganeseoxide, also available locally. Most of the white ornearly white sandstone, such as that near Tobati andPiribebuy, contains iron in the form of distinct particlesof magnetite (iron oxide); it should be easy to produceiron-free sand from such material by crushing andwashing, thus separating the iron particles by meansof gravity. In places where electricity is availablemagnetic methods of separating the iron-oxide mineralscould be employed.In addition to silica sand, the chief ingredients ofglass are feldspar and soda ash. Adequate suppliesof feldspar can almost certainly be found in the pegmatitesbetween Concepci6n and the Rio Apa. If not,or if transportation costs from that region are excessive,feldspar is a far cheaper commodity than finished glassand the requisite amounts could be imported. Thesame reasoning applies to soda ash, which is used inrelatively large amounts in glassmaking. There areno known deposits of sodium carbonate in Paraguay,but this is a cheap commodity and it would certainlybe cheaper to import soda ash than glassware.Glass factories require comparatively small capitalinvestments for machinery, and either wood or charcoalare adequate as fuels. Existing plants would requiremodernization, particularly in improved chemical controlof the raw materials and in control of temperaturesif any serious attempt is made to supplant imports.It is probable that the necessary technical skills arealready in the country, either among Paraguayanswho have learned glassmaking techniques in the existingfactories or among some of the immigrants fromGermany and other European countries.MINERAL PAINTSParaguay uses comparatively large quantities ofpaint for both exterior and interior decoration. Virtuallyall the paint needed is imported, either as pigmentor as prepared paints, yet there is abundant materiallocally to supply all the requirements for yellow, orange,pink, red, and brown colors that are used. This materialexists in the form of the rich iron ores near Caapucii, in