Tuesday, August 23, 2011

Today's Gems: Sandstone

sparkling sandstone ring and necklace

Sandstone is the second  most common sedimentary rock and consists of two parts: a grain component of quartz, feldspar, and lithic fragments; and the space between the grains which fills with silica or calcium carbonate during the lithification process.

Rocks called Moqui Marbles, named after the Moqui Indians of the western United States where these are commonly found, are compacted balls of sandstone encased in iron compounds. Geologists have several theories about how the stones are formed, some believe they are meteoric or even extraterrestrial in origin. The baseball shaped stones, sometimes referred to as "Shaman Stones," were used by Native American shamans for vision quests and other types of out-of-body journeys. They are still used by contemporary practitioners to release emotional blocks and stimulate Chi energy throughout the body.

Moqui Marbles (via canyoneeringusa.com)

Because sandstone is very resistant to erosion, it makes for a very durable building material. The Treasury building of Petra, modern day Jordan, was carved directly into the rock. It dates from the 4th century BC and still stands today. Other notable sandstone carvings are the temples of Abu Simbel, Egypt, built by Rameses II and carved out of a cliff on the west bank of the Nile.

The Treasury of Petra (via Google Images)

The Painted Desert in Arizona is a great example of cross bedding in the sedimentary rock. This occurs when strong forces of wind or water deposit the rock at a high velocity. It's easy to imagine the sandstone being swept and shaped over the Earth's surface.

The Painted Desert in Arizona (via britannica.com)
References: Smithsonian Rock and Gem by Ronald Louis Bonewitz; Gems of Wisdom, Gems of Power by Teresa Kennedy

Read related posts: Today's Gems

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