PHILOSOPHICAL SOCIETY OF WASHINGTON. 11 



Mr. F. M. Endlich read a memoir 



ON MINERALOGICAL SYSTEMS. 



Ever since the attention of naturalists was directed towards 

 minerals, the necessity of a system of classiacation for them has 



been felt. „ -, n . i 



Aristotle already (384-322 a. Chr. n.) classified all minerals 

 into dpvxtd (stones) and txsta.% ^^hra. (ores), the former as owing 

 their origin to the agency of humid vapor, the latter to dry gases. 

 Theophrast, and later Pliny, describe a number of minerals, many 

 of which may be recognized by the description, but no attempt 

 was made by either of them to assign them their respective posi- 

 tions in any definite system. The Arabian physician Avicenna 

 (about 1010 p. Chr. n.) separated the minerals into four classes, 

 viz., stones, inflammable fossils, salts, and metals. About the 

 same time Abul-Kihan-Albironny took the specific gravity of a 

 number of minerals, but no knowledge of any more important 

 investigations from that time has reached us. Basil Valentm is 

 said to" be the author of a little book published in the German 

 language about the year 1500, but this is most likely the work 

 of sevei-al German miners combined. Here we find for the first 

 time names like Quartz, Vries, Spat, &c. Georg Agricola, in his 

 "De Natura Fossilinm" (1546) has copied these names, and ap- 

 pears to be well acquainted with form, cleavage, hardness, gravity, 

 color, lustre, &c. of a large number of minerals. Later, in 1760, 

 the first impulse to study the /or?7i of minerals more carefully was 

 given by the Danish mineralogist Bartholin, who measured and 

 calculated the angles of the transparent Iceland double-spar. 

 After this time considerable attention was paid to the crystallo- 

 graphic part of mineralogy, the knowledge of which received a 

 very valuable addition by the assertion of the Dane Steno in 

 1669, that in rock crystal," in spite of unsymmetrical development 

 of the faces, the angles were constant. Investigations of this 

 kind, carried on by different mineralogists, tended to develop the 

 interest in the crystalline forms of minerals, and in 1735 Carl 

 Linne was the first naturalist who based a classification of the 

 minerals on their crystallographic character, in his " Systema 

 Natur£8, sive tria regna." "He still labored under the old pre- 

 vailing idea, that the salts chiefly produced crystalline forms, and 

 therefore called them "patres,'" as creating the crystals in the 

 "matrices.''^ He distinguished in bis classification : — 

 Petree, rocks ; MinevBe, minerals ; and 

 Fossilia, petrefactions. 

 Through these views Borne de Lisle was led to the study of 

 crystallography, and afterwards Baui/, in his " Essai d'une The- 

 rie sur la Structure des Crystaux" 1784, and 1801 in his "Traite 

 de Mineralogie" elevated crystallography to a special science. 

 The works of these excellent investigators had a great influence 



