Natural Gas Hydrates: H Structure

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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The H structure (for Hexagonal) consists of dodecahedra and two additional solids. First are 12-sided shapes consisting of squares, hexagons and pentagons (below right). Second are elongated "barrels" consisting of 12 pentagons and 8 hexagons (below left). The barrels can fit much larger hydrocarbons than methane.

The 4-5-6 faced solids cluster around the middle band of the barrels.

Below we see how the rear faces of one of the 4-5-6 faced solids connect to the barrel behind it.

The two shapes form a sheet of 4-5-6 faced polyhedra enclosing barrels.

The dimples in the sheet surrounded by four pentagons are in turn filled by dodecahedra, which enclose hexagonal holes. The holes fit over the barrels in the sheet below and accept the barrels from the next sheet above.

The oblique view below shows how the sheets stack.


Henriet, J.-P., Mienert, J., 1998; Gas hydrates : relevance to world margin stability and climate change, London : The Geological Society, Geological Society special publication no. 137, 338 p.

Kleinberg, Robert; Brewer, Peter, 2001; Probing gas hydrate deposits.  American Scientist. vol. 89; no. 3, Pages 244-251. 

Holder, Gerald-D (editor); Bishnoi, P. R. (editor), 2000; Gas hydrates; challenges for the future. Annals of the New York Academy of Sciences. 912; New York Academy of Sciences. New York, NY, United States. Pages: 1039.

Paull, Charles K. (editor); Dillon, William P. (editor), 2000; Natural gas hydrates; occurrence, distribution, and detection. Geophysical Monograph 124, American Geophysical Union. Washington, D.C., United States. Pages: 315. 

Haq, Bilal U., 1998; Gas hydrates; greenhouse nightmare? Energy panacea or pipe dream? GSA Today. vol. 8; 11, Pages 1-6. Geological Society of America (GSA). Boulder, CO, United States

Smelik, Eugene A.; King, H. E. Jr., 1997; Crystal-growth studies of natural gas clathrate hydrates using a pressurized optical cell. American Mineralogist. vol. 82; 1-2, Pages 88-98. Mineralogical Society of America. Washington, DC, United States.

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Created 1 August 2003, Last Update 14 Dec 2009

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