S. L. Penfield and G. S. Jamieson — Tychite. 217 



Art. XXIY. — On Tychite, a New Mineral from Borax ZaJce, 

 California, and on its Artificial Production and its 

 Relations to Northupite ; by S. L. Penfield and G-. S. 

 Jamieson. 



Historical. — -The new mineral to be described in this paper 

 was discovered by the merest chance in 1895, when some 

 minerals from Borax Lake, San Bernardino County, California, 

 were being studied by one of the present writers (Penfield). 

 At the time mentioned, word had been received from Mr. 

 Warren M. Foote of Philadelphia that he had some unknown 

 minerals from the Borax Lake region, and arrangement was 

 made for their examination in the mineralogical laboratory of 

 the Sheffield Scientific School. One of the minerals, which 

 proved to be a new species, consisted of octahedral crystals, 

 averaging about 3 mm in diameter, and concerning it Mr. Foote 

 wrote that it was a carbonate of magnesium and sodium con- 

 taining chlorine. The material sent for examination consisted 

 of a large number of the octahedral crystals, and from 

 amongst them a small one, which was perfect in form and 

 seemed to be in every way typical of the lot, was selected for 

 the purpose of making a. few preliminary tests. It was 

 brought in contact with a drop of nitric acid on a watch glass 

 and dissolved with effervescence ; the solution gave the flame 

 test for sodium, a minute drop of it gave the reaction for 

 magnesium with ammonia and sodium phosphate, but a test 

 for chlorine with silver nitrate gave a negative result. Think- 

 ing over what else might possibly be present, the idea of a 

 sulphate suggested itself, and a test with barium chloride 

 indicated the presence of the S0 4 radical. Accordingly, a 

 letter was sent to Mr. Foote informing him that there evidently 

 was some mistake, for the mineral he had sent proved to be a 

 sulphate and not a chloride. This elicited an immediate reply 

 from Mr. Foote, stating that, on the contrary, the mistake was 

 on our part, for he had always obtained the test for chlorine 

 and had repeated the experiment with like results ; thereupon 

 the test was repeated by us, and the presence of chlorine was 

 found in one crystal after another. The fact, therefore, was 

 established, that in the material sent there were two minerals 

 crystallizing in octahedrons, one containing the sulphate radi- 

 cal, the other chlorine, and that by chance a crystal of the 

 rarer sulphate happened to be the one first selected for making 

 the initial examination. A preliminary notice of the chlorine 

 compound was published by Mr. Foote,* who named the min- 

 eral northupite after Mr. C. H. Northup of San Jose, California, 



* This Journal (3), 1, p. 480, 1895. 



Am. Jour. Sci. — Fourth Series, Vol. XX, No. 117. — September, 1905. 

 15 



