March 17, 2013
Photographer: Bernardo Cesare; Bernardo's Web site
Summary Author: Bernardo Cesare
While studying samples of lavas from the Aeolian Islands off the west coast of Italy, I came across an interesting aggregate of crystals (glomerocryst). A photomicrograph thin section of the aggregate is featured above. Aeolian lava is studied to understand how magma forms at depth and the level of risk of its eruption. This particular glomerocryst is made of two minerals; plagioclase and pyroxene, whose chemical compositions, textures and melt inclusions help decipher just what happens in a magma chamber. But, if you look closely at its shape, you might learn something more -- that even something as hard as a rock has a heart. Photo taken on May 1, 2011 from the Geosciences Building at the University of Padua, Italy.
Photo details: Polarized light photomicrograph of a 30-micron thick rock slice (thin section); width of view is 3.5 mm. All pictures are taken with a digital camera mounted on a polarizing microscope, with crossed polarizers and the red tint plate (rotated as to reach the preferred colors). Software: Adobe Photoshop CS2 Macintosh.