Shards

Volcanic glass shards are fragments of the molten part of magma that cooled and solidified during eruption. Glass shards are typically remnants of tiny gas bubbles that developed and grew in size during the final ascent toward the surface; such shards may consist of many gas bubbles or only a portion of a single gas bubble. During eruption, the expanding gas broke the bubbles and surrounding glass into shards of various sizes and shapes. Shards formed by phreatomagmatic eruptions often have a particularly angular shape resulting from the violent explosive interaction between magma and water.

Bibliography

• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.

Photo
Y-shaped glass gragment in a Ignimbrite. PPL image, 10x (Field of view = 2mm)	Glass gragments in a Ignimbrite. PPL image, 10x (Field of view = 2mm)	Glass gragments in a Ignimbrite. PPL image, 10x (Field of view = 2mm)
Glass gragments in a Ignimbrite. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)
Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)
Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)
Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)
Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)	Glass gragments ( C- and Y-shaped) in a ignimbrite from S.Pietro island, Sardinia, Italy. PPL image, 10x (Field of view = 2mm)