• A geode in indirect sunlight, open on one end to reveal light orange spires and white spheres of quartz inside.
  • Detail of the white spherical grow inside the geode, clusters of textured white spheres through light orange spired and bumpy growth.
  • Looking down the spires of the geode, showing bulbous botryoidal growth in white and light orange. Some of the finer spire growth grows on an oddly attached bridge
  • The geode at another angle, showing the roof is coated with a fine dark mineral. The white spheres are highlighted in the shadows.
  • A side-view of the finer spires at the edge of the geode, showing they grow above the broken top
  • A side-view of the geode, which is conical and has an exterior of rough light brown rock.
  • Detail of spires on the edge of the geode, showing one is curled over like a candy cane.
  • Detail of the broken edge of the geode with the candy cane spire next to it. The broken edges have a layer of orange chalcedony coated with a milky white layer. Where there are partial spires, there is a dark point at the center, and at two points on the edge there is a metallic radial-growth mineral
  • Angled view of the specimen showing the roof of the geode is covered with another mineral growth.
  • Detail of a matte brown mineral growing in small angular crystals on the roof of the geode
  • Detail of the stalactitic growth on one edge, with the candy cane formation and a tall spire that is colorless in the end and light orange in the base.
  • Detail looking down the spires, showing the candy-cane spire grows off an odd bridge-like growth.
  • The piece on a measuring mat, measuring a bit over three and a half inches long and tapered from less than a inch at the base to two and a half inches at the wide top.
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Stalactitic chalcedony geode

Stalactitic chalcedony geode

$55.00 USD
$55.00 USD
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Locale: Atlas Mountains, Morocco

Approx dimensions: 3.5 x 2.25 x 2"

Approx weight: 229g

 

These unusual geodes from Morocco are like small caves lined with stalactites, botryoidal forms, and swirling agate patterns. 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. This creates a colorless-to-white growth over the orange chalcedony, which can produce a soft orange-cream druzy coating, or bold Halloween patterns of orange and white stripey stalactites. This specimen is one of my favorites of this material, with unusually-formed stalactites and botryoidal growth.

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). Specimens including this one feature lovely snowy white spheres of radial growth quartz.

Where stalactites have broken you can see a pinpoint of a dark, metallic, mineral at the core, surrounded by orange chalcedony, then translucent white chalcedony. This piece has a unique curved candy-cane stalactite. The roof of the geode is coated with small angular brown minerals (unknown; I have not been able to find info on common associates of this material but it looks similar to andradite). I would love to know more about how these formed. I have observed many are “ice cream cone” shaped—technically speaking, “conical”—like this specimen.

UV reactivity Small amounts of calcite fluoresce and phosphoresce peachy red under 365nm UV light.

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