scoria - large display specimen of maroon scoriaceous basalt from a satellite cone on Mauna Loa
Scoria is the silica poor equivalent of pumice. Lava with a low silica content is runny, so gas bubbles tend to coalesce to form larger bubbles in basalt. In a silica rich granitic magma, high viscosity prevents bubbles from coalescing, so there are many more, but smaller, gas bubbles in pumice, one reason it floats longer in water.
This scoria is surprisingly light and is amazingly red from the oxidation of hematite. It was collected at an elevation of 10,500 feet on the north slope of Mauna Loa, from a mass of blocks, scoria and cinder associated with a satellite cone that was quarried for road material. An interesting example from a famous volcano.
The field photo looks down on the University of Tokyo's ASHRA observatory in a lava field at 3,300 meters (10,826 feet) on Mauna Loa. This observatory is an All-Sky High Resolution Air-shower detector which simultaneously monitors and images Cherenkov showers, fluorescence and star light. NOAA operates the Mauna Loa Observatory 97 meters higher on Mauna Loa. Both are above the inversion that separates the more polluted lower atmosphere from the cleaner free troposphere. MLO has been collecting data related to atmospheric change since the 1950s.
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