Spherulites are spherical structures that typically appear in glass-rich igneous rocks, especially rhyolites and obsidian. Paso de los Indios locality, Chubut Province, Argentina.
Las esferulitas son estructuras esféricas que normalmente
aparecen en rocas ígneas ricas en vidrio, sobre todo en riolitas y obsidianas.
Foto: esferulitas de distintos colores de la localidad de Paso de los Indios.
Pcia. del Chubut. Argentina.
Spherulites are spherical structures that typically appear
in glass-rich igneous rocks, especially rhyolites and obsidian. Photo:
Spherulites of different colors from the Paso de los Indios locality, Chubut
Province, Argentina.
Jaspillita. BIF (Banded Iron Formation) Roca sedimentaria bandeada de Jaspe rojo y hematita. 189 milllones de años. Jurásico. Cordillera del Viento. Provincia de Neuquén. Argentina.
Jaspillite. BIF
(Banded Iron Formation). Banded sedimentary rock of red jasper and hematite.
189 million years old. Jurassic. Cordillera del Viento. Neuquén Province,
Argentina.
Red volcanic slag
(porous basaltic lava). Its color is due to the oxidation of its iron content
by oxygen in the air. Seidisholar, Grimnesi Area. Iceland.
Fulgurita: Nombre que proviene del latín fulgur,
“relámpago”. Es sílice vitrificada. Impactita producida por rayo sobre arena,
el impacto hace que los granos de sílice se fundan y se fusionen con
posterioridad, formando una especie de raíz hueca de poco grosor y gran
ramificación. Estas estructuras se pueden hallar en desiertos y dunas
litorales. Material muy frágil.
Fulgurite: Name that comes from the Latin fulgur,
"lightning". It is vitrified silica. Impactite produced by lightning
on sand, the impact causes the silica grains to melt and subsequently fuse,
forming a kind of hollow root of little thickness and great ramification. These
structures can be found in deserts and coastal dunes. Very fragile material.
Museo Mineralis. Argentina.
Tektite: Impactite. Name derived
from the Greek "Tektos" which means melted. Natural gray to black
glass produced by meteorite impact. Its composition highlights the low presence
of water and molten zircon. This material can be hundreds of kilometers away
from the impact site. They are found in North America, Central Europe, West
Africa, Australia and Asia, they are given different names depending on their
location (Indochinite, Filipinite, Australite). Age: According to locality
between 0.7 and 35 million years. Ornamental use.
Desert glass:
Impactite. Light yellow natural glass found in the deserts of eastern Libya and
western Egypt (1932). Meteorite impact product (site not located). Age: 29
million years. It was used as a gem in Tutankhamun's scarab-shaped pectoral.
Ornamental use, gem. lithic tools.
Museo Mineralis. Argentina.
Slag: Impactite. Glassy material produced by meteorite
impact. (Crater not found). Age: 3.3 million years. (Middle Pliocene). Also
called Chapadmalal slag (Prov. of Bs.As. Mar del Plata. Argentina). Its origin
was much discussed, at first it was given a volcanic origin, Florentino
Ameghino believed that it was a consequence of primitive man's campfires or
grassland fires, another theory says that they were the product of the chemical
reaction between minerals and groundwater and therefore last a cosmic origin by
meteorite impact (accepted current theory). Mineral Museum. Argentina.
