140 CLASSIFICATION OF THE PUBLIC LANDS. 



Pyrite is found in fissure veins and along the bedding planes of 

 sedimentary and metamorphic rocks. It occurs in various other 

 forms in rocks of practically all kinds and ages. Graphite is found 

 mainly in the older crystalline metamorphic rocks in embedded masses 

 and veins, although in some places it occurs in beds. 



Asbestos is an alteration product found in veins in older crystal- 

 line rocks. Magnesite is also generally regarded as an alteration 

 product and is found in veins as well as in bedlike masses. Some 

 abrasives, like corundum, emery, and garnet, occur in small crystals, 

 principally in veins in igneous and metamorphic rocks. 



Some asphalt impregnates sands, sandstones, and limestones and 

 occurs in veins in these rocks. Other hydrocarbons, such as gilsonite 

 and ozokerite, are found in veins or fissures, usually in sandstones. 



Mineral waters are, of course, obtained from springs; and some 

 common salt and sulphur, as well as the materials of some mineral 

 paints, are obtained from deposits formed by the evaporation of 

 spring water. Bromine is found in natural brines and bitterns. 



Guano occurs in massive deposits, which in some regions are of 

 considerable thickness. It is usually found in caves or other pro- 

 tected places. Peat results from the accumulation in bogs of plant 

 remains that have undergone slight modification at the top, although 

 if the deposit is thick its lower portion may have been reduced to a 

 mass somewhat resembling lignite. 



Sections 2320 to 2325, inclusive, of the Revised Statutes prescribe 

 certain rules and regulations to govern the location and patenting of 

 "■ mining claims upon veins or lodes of quartz or other rock in place 

 bearing gold, silver, cinnabar, lead, tin, copper, or other valuable 

 deposits." Section 2329 provides for " claims usually called ' placers,' 

 including all forms of deposit, excepting veins of quartz or other 

 rock in place." Thus, although the minerals in the foregoing list 

 exist in nature in beds, in veins, in massive form, or as liquids, or 

 even in more than one of these forms, the law divides them into only 

 two great classes — those which occur in veins or lodes of quartz or 

 other rock in place and those usually called placers, including all 

 other forms of deposits. The distinctions as to mode of occurrence 

 of these minerals in nature are considered in classifying as mineral or 

 nonmineral the lands containing them; such distinctions are the 

 primary factors that under the present mining laws must always be 

 considered in determining the law under which the deposits may be 

 acquired. 



A large part of the information heretofore obtained by the Geolog- 

 ical Survey regarding these minerals has been gathered in reconnais- 

 sance examinations and in connection with reports on mineral re- 

 sources, with the result that in most of the areas examined much 

 geologic information that would be necessary for land classification 



