Great South Gems & Minerals
• Geode • (Mexico)
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• Geode •
Geodes
Commonly called "Trancas" by the locals. These 2" to 3-1/2" geodes are usually lined with quartz crystals and/or calcite or aragonite. Read article about Cracking Geodes open (without destroying them!). New Low Price! Only $3.75 each! (While supplies last). We have about 2,000 in stock right now. These geodes are whole... you break them. Guaranteed to be hollow.
Geodes are rock formations which occur in sedimentary and certain
volcanic rocks. They are normally spherical in shape and has a
cavity, or vug, in which internal crystal formations or concentric
banding. The exterior of the most common geodes is generally
limestone or a related rock, while the interior contains silica, or
quartz crystals and/or chalcedony. Other geodes are completely
filled with crystals, being solid all the way through. These types
of geodes are called nodules. The only difference between a geode
and a nodule is that a geode has a hollow cavity, and a nodule is solid.
See: en.wikipedia.org/wiki/Geode
www.igsb.uiowa.edu/browse/geodes/geodes.htm
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Geodes begin as bubbles in volcanic rock or as animal burrows, tree
roots or mud balls in sedimentary rock. Over time, the outer shell of
the spherical shape hardens, and water containing silica
precipitation forms on the inside walls of the hollow cavity within
the geode. The silica precipitation can contain any variety of
dissolved minerals, the most common being
quartz,
but amethyst and calcite are also found. Occasionally, and rarely, a
geode if found to contain the original water still trapped
within. These rarities are called enhydros.
See our links to other
geodes:
www.greatsouth.net/minerals/M146_Geode_Matched_Halves.html
www.greatsouth.net/minerals/p-M248.html
| Price: $3.75 |
| M134 Whole Mexican Geode (Mexico) |
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