Geochemistry, Mineralogy, Petrology & Volcanology

Imaggeo On Monday: Nature of ice crystals

Katarzyna Walczak December 21, 2020

Nature of ice crystals . Credit: Katarzyna Walczak (distributed via imaggeo.egu.eu)

Moisture coming from the ground is freezing at the entrances of small ground pockets, shaping wonderful natural ice crystals, during a very cold and dry winter in Poland in 2019. Description by Katarzyna Walczak, after the description on imaggeo.egu.eu. Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and video ...[Read More]

Imaggeo On Monday: Lahar in the jungle, Mexico

Velio Coviello October 5, 2020

Lahar in the jungle, Mexico. Credit: Velio Coviello (distributed via imaggeo.egu.eu)

Volcán de Colima currently is the most active volcano in Mexico where many rain-induced lahars occur every year. La Lumbre ravine is the ephemeral channel that drains the west-southwestern slopes of the volcano. In 2016, while Volcán de Colima experienced a prolonged explosive phase, several lahars were documented in this channel. One of them is shown in his picture, taken on August 13, 2016, du ...[Read More]

Imaggeo On Monday: Blue Olivine in an unusual basalt

Bernardo Cesare September 28, 2020

Blue Olivine in an unusual basalt. Credit: Bernardo Cesare (distributed via imaggeo.egu.eu)

Blue Olivine set in a matrix of pyroxene, magnetite and plagioclase in a basalt collected by the photographer, Bernardo Cesare, on the shore of the Sea of Galilee, Israel. Polarized light photomicrograph. Crossed polarizers and red tint plate. Width c. 2.7 mm. Who may have been throwing this stone a couple millennia ago? Description by Bernardo Cesare, after the description on imaggeo.egu.e ...[Read More]

Friedrich Mohs and the mineral scale of hardness

Hazel Gibson September 25, 2020

Image credit: Hazel Gibson

One of the most famous identification methods in the study of mineralogy is the Mohs Scale of Hardness. A comparative scale, based on the hardness of each mineral, it is a way geoscientists can compare minerals to each other and organise them based upon an easily testable physical characteristic. Each level of hardness has a value, from 1 (the softest) to 10 (the hardest) and each number is associ ...[Read More]