. . . describes one which he heard in the Serra de Piratininga [in southern Brazil], as resembling the discharges of many pieces of artillery at once. The Indians who were with him told him it was 'an explosion of stones'; 'and it was so,' he says; 'for after some days the place was found where a rock had burst, and from its entrails with the report which we had heard, like the groans of parturition, had sent to light a little treasure. This was a sort of nut, about the shape and size of a bull's heart, full of jewelry of different colours, some white, like transparent chrystal, others of a fine red, and some between red and white, imperfect, as it seemed, and not yet completely formed by nature. All these were placed in order, like the grains of a pomegranate, within a case or shell harder than even iron; which, either with the force of the explosion, or from striking aginst the rocks, when it fell, broke in pieces, and thus discovered its wealth.'Vasconcellos concluded, "the philosophy of these things is understood," . . . but it is not necessary to dwell on his "philosophy" here.
Next, the anonymous authority summoned the testimony of Nichol·s del Techo (1611-1684), a Jesuit missionary in Paraguay.
Techo notices the same thing in the adjoining province of Guayra, "famous," he says, "for a sort of stones which nature, after a wonderful manner, produces in an oval stone case, about the bigness of a man's head. These stone cases lying under ground, when they come to a certain maturity, fly like bombs in pieces about the air, with much noise, and scatter about abundance of very beautiful stones, – but these stones are of no value."
The Spaniard Christoval d' AcuÒa (1597-1675), a Jesuit missionary to Chile and Peru who accompanied Pedro Texiera on his exploration of the Amazon River in 1638, is the next observer to be cited.
In the account of Texiera's voyage down the Orellana [Ecuador], d' AcuÒa says, the Indians assured them, that "horrible noises were heard in the Serra de Paraguaxo from time to time, which is a certain sign that this mountain contains stones of a great value in its entrails."Finally, the same unnamed author dismissed the speculation of Alexander von Humboldt (1769-1859), the German naturalist and explorer who, at his own expense and with only the companionship and assistance of the French botanist Aimé Bonpland, completed a five-year, 6,000-mile scientific exploration of Central and South America.
The opinion of the Indians then, concerning these explosions seems uniformly to refer them to the same cause: but what these natural grenades may be, must be left for others to ascertain.
Humboldt, noticing a remark of M. Lafond, that there are hills in Mexico, abounding in coal, from which a subterraneous noise is heard at a distance, like the discharge of artillery, asks, whether "this curious phenomenon announces a disengagement of hydrogen produced by a bed of coal in a state of inflammation?" – It seems too frequent and too general for this solution.
1. The Quarterly Review (London, 1815) Vol. XII: Oct. 1814 & Jan. 1815, pp. 343-44.