Here, in a good climate, at 2000 feet elevation, are found auriferous veins of great richness. They are of quartz mixed with decomposed feldspathic rocks, and have yielded very lucrative bonanzas. The first mine was Guapinol, one bonanza of which produced $1,000,000. Several other mines were worked, from one of which (Los Castros) $2,000,000 were taken in a few years. It is estimated, from the best data obtainable, that about £1,000,000 have been taken from Monte Aguacate. Several of these veins are from six to seven feet wide, but that called the Quebrada Honda is sixteen feet wide. Most of the ore is of a high grade and of refractory character. It is probable that the whole southwestern slope of the Guatusos and Miravalles ranges of mountains is auriferous. The rocks in the northwestern extension of this district consist principally of feldspar, porphyry, basalt and dolorite. The gold veins nearly all ran northeast and southwest, and are encased in feldspar, sometimes in porphyry, and occasionally in basalt. They consist, in great part, of crystalline quartz, and are from two to forty feet wide. Professor Pittier also found gold in the slopes of the Buena Vista mountain. Gold is further found in the Talamanca mountains, especially in the placer grounds of the Duedi River, and on the inferior hills between the Lari and Coen rivers. Along the latter, and near Akbeta, also on the shore of Puerto Viejo, iron exists. Copper and silver, Professor Pittier says, have been discovered in Diquis, between Paso Real and Lagarto, and native copper in Puriscal. Other mines are included in the following table: The Principal Mines Registered in 1892.