PREFATORY NOTE. 



The accompanying handbook and guide is an outgrowth of the work 

 of installing and lalx'ling the colh^-tions of the economic .section of the 

 Division of Physical and C-luMnical (leoU)gy. The term nonmetallic, 

 as used, includes those minerals which, as here exhibited, are utilized 

 in other than metallic forms. The collections, comprising as now 

 arranged, sonui ^^,500 specimens, include therefore some materials 

 which— like the iron oxides — may ))e utilized as ores of metals. As 

 such they have already been considered in Bulletin No. 42, under the 

 title A Preliminary Descriptive Catalogue of the Systematic Collec- 

 tions in Economic Geology and Metallurgy, by F. P. Dewey. The 

 collection of l)uilding and ornamental stones which might perhaps be 

 included herewith has been also the subject of a special handbook 

 pul)lished in the Annual Report of the National Museum for 1880, 

 and entitled The Collection of Building and Ornamental Stones in the 

 United States National Museum: A Handbook and Catalogue. By 

 George P. Merrill. 



It is scarcely necessary to remark that in the preparation of this 

 work the curator has ))een hampered by a great dearth of information 

 on certain subjects and burdened with a superabundance on others. 

 Certain materials, such as the coals, phosphates, limes, and cements, 

 would each require a volume, and necessarily must be very imper- 

 fectly treated here. In such cases the curator has aimed to give as 

 brief and concise an abstract as the reipiiniments of a handbook 

 would p(!rmit, and make up for the deficiencies in the l)i])liography. 

 In oth(;r cases the subjects are treated as fully as the knowledge at 

 hand will allow. In descri])ing occurrences the aim has ])een to give 

 in detail one or two fairly typical deposits, referring to others more 

 brierty. Naturally the preference has l)een given to American mate- 

 rials. Statements as to prices and annual production are (juite unsatis- 

 factory and of very temporary value at best. But little space has 

 therefore been devoted to this branch of the su))ject. Technical, 

 chemical, and crystallographic points have been but lightly touched 

 upon, such being already covered by existing literature. Only such 

 statements as to hardness, color, etc., are given as it is thought may 

 be of value in rough preliminary deternunations. 



The satisfactory installation and classification of collections of this 

 nature are matters of no inconsiderable difficulty. As the materials 



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