• A chalcedony geode with a thick crust in indirect sunlight. Half if it is open to a deep geode, while the other half is solid. The solid side is half covered with matrix, and half solid exposed chalcedony.
  • The specimen angled to look further into the deep dark geode. There is a white formation at the back with small spherical white minerals spotting the dark red-brown surface.
  • Looking into the geode emphasizing to opposite wall, coated in dark red-brown chalcedony and spotted with white minerals.
  • Side-view of the geode, with the open end slanted
  • Side-view of the geode, which is conical with a flat top and base. The outside of the geode is covered with a light brown pocked rock
  • The geode in full sunlight, looking into the back where the white radial quartz growth glitters.
  • Looking into the geode, with focus on a cluster of white minerals at the entrance including small calcites
  • Detail of the quarter of the geode with exposed chalcedony, a dark warm gray color swirling with red and orange.
  • Detail of a cluster of blade-like growth with small double-terminated calcite crystals sprinkled on top.
  • Scale image of the specimen on a measuring mat, measuring about four inches square but tapered down to about two inches at the base.
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Stalactitic chalcedony geode "The Pie Chart"

Stalactitic chalcedony geode "The Pie Chart"

$65.00 USD
$65.00 USD
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Locale: Atlas Mountains, Morocco

Approx dimensions: 4 x 4 x 3"

Approx weight: 588g

 

These unusual geodes from Morocco are like small caves lined with stalactites, botryoidal forms, and swirling agate patterns—though this one completely lacks the stalactitic growth forms common to this region. While commonly called red chalcedony, I find the color is more orange to red-orange. Hematite causes this coloration, but later phases of growth (“second generation”) don’t contain hematite inclusions and are white.

I call this one "the pie chart": one quarter matrix, one quarter swirling chalcedony, and 1/2 a beautiful geode. It's difficult to photograph to the back of the geode because it curves off into darkness. A snow-drift of white quartz flows out of the darkness, accompanied by fuzzy white snowballs of radial-growth quartz. Since chalcedony and quartz are closely related you often see them grow together. They have the same chemical composition (silica) but different crystal structure (cryptocrystalline vs. crystalline).

UV reactivity Near the geode entrance, a cluster of white blade-like growth is sprinkled with small double-terminated calcite crystals, which fluoresce and phosphoresce peachy-red under 365nm UV light. The chalcedony section fluoresces white.

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