32 REPORT OF NATIONAL MUSEUM, 1889. 



attractive, still the typical average material as found at the mine or 

 quarry is deemed of first importance. 



The size of the specimens in these collections from necessity varies 

 greatly, and whenever space will allow regard is had to the individual 

 characteristic of eacli sample. When the material is massive and hom- 

 ogeneous throughout the standard adopted is about 5 inches square on 

 the face and some 2 inches thick. It is obvious, however, that such 

 sizes are not applicable to all grades and kiuds of materials, and in the 

 exhibits may be seen specimens varying from less than an ounce to 

 over 200 pounds in weight. Material in form of a powder is as a rule 

 exhibited in bottles of from 4 to 10 ounces capacity. 



The following list will serve to give an idea of the character and va- 

 riety of materials here to be exhibited though, unfortunately, the ar- 

 rangement of the exhibition space is not such as to enable us to carry 

 it out in a manner as systematic as might be desired. 



(1) Stones used for purposes of building or ornamentation : 



1. The crystalline siliceous rocks, both massive and schistose : Granite, syen- 

 ite, diabase, gabbro, diorite, liparite, trachyte, basalt, andesite, gneiss, and the 

 crystalline schists. 



2. The calcareous rocks ; Limestones and dolomites, both marbles and com- 

 mon varieties ; alabaster. 



3. The serpentines and verdantique marbles. 



4. Fragmeutal rocks; Sandstones, conglomerate, breccia, and clay slate. 



4. Minor stones used for decorative work. (See Gem collection.) Precious 

 serpentine, jasper, malachite, agate, etc. 



(2) Stones used in the manufacture of cements, mortars, etc.: Limestone, both hydraulic 



and the common varieties, gypsum. 



(3) Natural abrading and polishing materials, (a) Materials used in the massive 



form : Grindstones, whetstones, grits, and pumice, (b) Materials used only in 

 pulverulent form ; Quartz sand, garnet sand, crude topaz, pumice dust, emery 

 and corundum, black diamond (bort). (c) Polishing powders: Infusorial earth, 

 tripoli, rottenstone, chalk, etc. 



(4) Natural fertilizing substances, (a) Phosphatic and alkaline : Apatite, phosphatic 



sandstone, phosphorites, guano, greensand, bone phosphate, orthoclase and 

 salts of potash, (b) Calcareous and carbonaceous: Limestone, marl, gypsum 

 muck, and vegetable mold. 



(5) Sulphur and salts used in chemical manufacture. 



(6) Fictile materials, (a) Clay for brick, tiles, stoneware, potters and pipe clay. 



(&) Kaolin, porcelain clays, and feldspar, (c) Glass-making materials, (d) 

 Graphite for pencils and crucibles. 



(7) Detergents, pigments, adulterants, mineral lubricators, etc. 



(8) Ores of the precious aud baser metals; gold, silver, platinum, iridium, osmium, 



aluminum, copper, zinc, lead, mercury, iron, manganese, tin, nickel and cobalt, 

 bismuth, antimony, arsenicum, chromium, cerium, cadmium, tellurium, uran- 

 ium, etc. 



(9) Useful substances of the carbon group, (a) The coals ; anthracite, bituminous, 



and cannel coal, lignite, peat, jet. (b) Asphalt and allied substances ; asphalt 

 bitumen, paraffiue, elaterite, ozokerite, amber, aud other fossil resins, (c) 

 Liquid and gaseous hydrocarbons ; crude petroleum, lubricating oils, illumi- 

 nating oil, naphtha, benzine, paraffiue, natural gas, etc. 



