porphyrschiefer

Updated: May 13, 2025

These masses were the same as the porphyrschiefer of the mountain of Bilin in Bohemia; we recognised in them small long crystals of vitreous feldspar.

Alexander von Humboldt - Personal Narrative of Travels to the Equinoctial Regions of America, During the Year 1799-1804 — Volume 1

It is the real porphyrschiefer of Werner; and it would be difficult to distinguish, in a collection of stones, the phonolite of Parapara from that of Bilin, in Bohemia. It does not, however, here form rocks in grotesque shapes, but little hills covered with tabular blocks, large plates extremely sonorous, translucid on the edges, and wounding the hands when broken.

Alexander von Humboldt - Personal Narrative of Travels to the Equinoctial Regions of America, During the Year 1799-1804 — Volume 2