Notice of the Occurrence of a Tungstate of Lime and Copper in Lower California.
BY J. D. WHITNEY.
Among some specimens brought from the vicinity of La Paz, Lower California, by Mr. Rémond, about three years since, was one which attracted my attention, as it seemed to contain an undescribed mineral. I therefore made an analysis of it and found it to consist of tungstic acid, oxide of copper, and lime, with a small quantity of water, probably not essential to its composition. The results of the analysis were as follows:
| Tungstic Acid | 79.69 |
| Oxide of Copper | 6.77 |
| Lime | 10.95 |
| Protoxide of Iron | .31 |
| Water | 1.40 |
| 99.12 |
On examining to ascertain if there was any known mineral having a composition similar to this, I found that a tungstate of lime containing copper had been described by Domeyko as occurring in the copper mines of Llamuco, near Chuapa, in the province of Coquimbo, in Chili, where it was discovered by M. Gay (Annales des Mines (4) iii, 15). That mineral, however, only contained 3.3 per cent. of oxide of copper, while the one of which the analysis is given above contains 6.77 per cent. of that substance. M. Domeyko calls the mineral analyzed by him “Scheelin calcaire cuivreux,” but does not attempt to give a formula for it, or to decide whether it is entitled to rank as a distinct species.
The Lower California mineral, of which the analysis is given above, occurs in a red metamorphic rock, associated with black tourmaline. It is crystalline-granular in structure, with a distinct cleavage in one direction, and seems to be homogeneous throughout. Its hardness is about that of Scheelite; luster, highly vitreous; streak, very light greenish-gray; color, pistachio green, passing to olive and leek green. Before the blowpipe in the glass tube it blackens, and gives off a little water. On charcoal it blackens instantly, becomes rounded on the edges, with a little intumescence, and gradually acquires the appearance of a slag, in which numerous fine points of metallic copper are seen. With the fluxes it gives the reactions of tungstic acid and copper. It is easily dissolved by chlorohydric acid, with separation of tungstic acid.
From the appearance of the mineral, I am inclined to regard it as having a definite composition, represented by the formula CuO WO₃+2 (CaO WO₃); this formula would require the following composition:
| Tungstic Acid | 78.43 |
| Oxide of Copper | 8.95 |
| Lime | 12.62 |
| 100.00 |
This agrees pretty well with the results of the analysis, although it is desirable that more specimens should be examined, and if possible from other localities. I am informed by Mr. Ashburner that he has noticed this mineral at more than one mine in Lower California.
At all events, I would suggest for the mineral in question the name of Cuproscheelite, as convenient for designating it, and as expressing its chemical and mineralogical relations, whether it be considered as a mineral substance having a distinct and fixed composition, or only as a variety of Scheelite, containing a large but uncertain amount of oxide of copper.
Dr. Ayres called attention to the fact that a carcase of a Black fish could be procured at the Potrero, at a small expense, and a subscription was raised for its purchase.
Professor Whitney exhibited a branch of Sequoia sempervirens, taken from a small tree growing near San Rafael, of which the leaves are entirely white. The tree presents a very singular appearance, surrounded as it is by other redwoods of the usual color. The fact was elicited that similar blanched redwoods exist in other localities in the Coast Ranges; but no explanation or theory was offered to account for this curious, abnormal blanching of the foliage of a single species—a similar condition of things not having been noticed, so far as known, in any other species than the redwood.