314 



SCIENCE 



[N. S. Vol. XXVII. No. 68& 



exposed rock surface about 2J by 4 feet were 

 over 200 more or less imperfect benitoite crys- 

 tals, amid thin patches of remaining natrolite, 

 the whole standing out prominently from the 

 surrounding rough and unprotected surface 

 of the schist. 



The altered portions of the schist are full 

 of cracks and cavities, varying in size up to 

 two or three inches in width, and having a 

 rough orientation parallel to the planes of 

 schistosity. The cavities are for the most 

 part filled with natrolite, with which benitoite 

 or carlosite or both are often associated. The 

 natrolite is not always accompanied by beni- 

 toite and carlosite, but in no instance noted 

 did the benitoite occur without the natrolite 

 and in only a few cases was the carlosite found 

 alone. A soft dark brown mineral substance, 

 resembling cadmium oxide, is also sometimes 

 associated with the natrolite. It is not un- 

 common to find the cavities only partially 

 filled, in which ease the occurrence resembles 

 a geode, the crystals of the natrolite (some- 

 times associated with benitoite and carlosite) 

 forming the inner surface. The natrolite in 

 such cases is usually coated with a brownish 

 or brownish-yellow stain, or is covered by an 

 intricate mass of microscopic, needle-like crys- 

 tals of a peculiar greenish-drab color. 



As a usual thing the benitoite and carlosite 

 are in contact with the country rock, the car- 

 losite sometimes having one extremity buried 

 in it, while the remainder of the crystal ex- 

 tends into the natrolite. One instance was 

 noted where a long slender carlosite crystal 

 extended across a vein of natrolite with an 

 extremity penetrating the schist on either side. 

 The facts above noted imply the crystallization 

 of the benitoite and carlosite previous to the 

 complete deposition of the natrolite. Isolated 

 crystals of the benitoite and carlosite are not 

 rare in masses of natrolite, however, so that 

 possibly the crystallization of the three min- 

 erals was practically contemporaneous, at least 

 in certain instances. In some cases the beni- 

 toite appears to be entirely surrounded by the 

 schist, but a close examination usually reveals 

 a thin film of natrolite between the former 

 and the country rock. In the places where 

 the carlosite occurs alone or associated with 



only minor quantities of natrolite, the carlos- 

 ite is in the form of thin veins, the crystals 

 being imperfect and forming a series of thin 

 plates or flakes. Close associations of the 

 benitoite and carlosite are not uncommon and 

 indicate contemporaneity of origin for the two 

 minerals. No alteration of the natrolite or 

 benitoite was noticed, but red stains resembling 

 iron oxide were seen emanating from around 

 several of the carlosite crystals. Mr. Schaller 

 has called the writer's attention to the fact 

 that minute fragments of the carlosite also 

 show a brick-red color, so that the coloring 

 around the crystals may be due to fine particles 

 of the unaltered mineral. 



Development work has so far been confined 

 to near the middle of the schist lens, and con- 

 sists of a tunnel and several open cuts follow- 

 ing the strike of the schist. The tunnel is 

 50 feet long and the largest cut 10 feet deep, 

 4 feet wide and 14 feet long. The gems are 

 secured either by pounding up the richer por- 

 tions of the matrix and then picking out the 

 few crystals or fragments that have withstood 

 the shock, or else chiseling out the larger indi- 

 vidual crystals at the expense of the smaller 

 surrounding ones. Only a small percentage 

 of the gems are saved by either method, as the 

 crystals are very brittle and usually consider- 

 ably jointed and cracked. The present value 

 of the cut stones is said to be $40 per carat. 

 Ealph Arnold 



COALINGA, CALIFOENLi, 



September, 1907 



NOTES ON ORGANIC CHEMISTRY 



KETEN 



A NUMBER of derivatives of ketone hava 

 been known for some time and the announce- 

 ment has just been made of the preparation 

 of the parent compound.^ This substance is 

 of great interest because it is the simplest 

 member of the highly important class of 

 ketones and, moreover, it is the simplest an- 

 hydride of acetic acid. Its mode of forma- 

 tion and reactions show that its formula is 

 H.,C : CO, i. e., it is methylene ketone; the 



^N. G. M. Wilsmore, Jour. Chem. Soc. (Lon- 

 don), 91, 193S (1907). 



