Sulphur Mountain of Ticsan.

—“In following the Cordillera of the Andes towards the south,” says M. Humboldt, “what was my surprise, when on the other side of the equator, I found that the celebrated sulphur mountain of Ticsan (lat. 2° 10′ S.) between Quito and Cuença, was not composed either of trachyte or limestone, or gypsum, but of mica slate.

This mountain of sulphur, called Quello by the Indians, is, according to my barometric measurement, 1250 toises above the sea.

It is composed entirely of primitive mica slate, which is not even anthracitic as are the transition varieties of this rock.

In the ravines between Ticsan and Alausi, it is seen reposing on gneiss.

The sulphur is contained in a bed of quartz more than 1200 feet thick, regularly directed N. 18° E., and inclined like the mica slate 70° or 80° to the N.W. The bed of quartz is worked open to-day.

The side of Cerro Quello, in which the works were commenced ages ago, is opposed to the S.S.E., and the bed appears to prolong itself towards the N.N.W. At the same time, sulphur has not been found at the surface of the earth in that direction, at 2000 toises from Ticsan.

The whole is covered by a thick vegetation.”

Towards the end of the eighteenth century, masses of sulphur were found from two to three feet in diameter; at present, strata much poorer are worked, the sulphur being disseminated through them in lumps from three to four inches in thickness.

It is observed, that the sulphur increases in quantity with the depth of the works, but these are arranged so badly, that the lower strata are almost inaccessible.

As the quartz contains no fissures or cavities, no specimens of crystallized sulphur have been found.

The sulphur does not form, as might perhaps have been supposed, a mass or collection of veins, but is disseminated in small masses, having no continuity with each other, in the quartz which traverses the mica slate parallel to its strata.

The apertures, by which perhaps they have been united, are no longer visible; but all the quartz has suffered a singular change.

It is dull, frequently friable, and breaks in some places with the slightest blow, which indicates splits or cracks, which are inappreciable to the sight.

The temperature of the rock does not differ from that of the atmosphere.

The inhabitants are in the habit of attributing the earthquakes to which their country has been exposed, to the concavities which they suppose to exist beneath the sulphur mountain.

In the great catastrophe of the 4th of February 1797, which destroyed so many thousand Indians in the province of Quito, the three places where there is most sulphur, the Cerro Quello, the Azufral de Cuesaca near the town of Sbarra, and the Machay of St. Simon, near the volcano of Antisana were only slightly agitated; but at a previous period, an explosion resembling that of a mine occurred in the bed of quartz itself, which contains the sulphur near Ticsan.—Ann. de Chim. xxvii. 131.