Euhedral

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This is an old revision of this page, as edited by 213.70.217.172 (talk) at 11:13, 17 November 2011 (corrected etymology - see http://en.wiktionary.org/wiki/%CE%B5%E1%BD%96#Ancient_Greek). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Euhedral pyrite crystals

Euhedral crystals are those that are well-formed with sharp, easily recognised faces. Normally, crystals do not form smooth faces or sharp crystal outlines. Many crystals grow from cooling liquid magma. As magma cools, the crystals grow and eventually touch each other, preventing crystal faces from forming properly or at all.

However, when snowflakes crystallize, they do not touch each other. Thus, snowflakes form euhedral, six-sided twinned crystals. In rocks, the presence of euhedral crystals may signify that they formed early in the crystallization of a magma or perhaps crystallized in a cavity or vug, without hindrance from other crystals.

Etymology: Euhedral is derived from the Greek eu meaning well, good and hedron meaning shape.

See also

References

  • Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., Wiley, p. 15 ISBN 0-471-80580-7
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