Dwarves Earth Treasures: Thundereggs from Trancas Mine, Chihuahua Province, Mexico

Trancas "Geodes" Thundereggs
Trancas Mine, Chihuahua Province, Mexico

Trancas Geodes are one of many geode-type thundereggs coming from Mexico and they're popular for the purpose of "Geode-cracking" which exposes the hydrothermal quartz crystals often in very weird shapes such as "fingers", "mushrooms", and "Scepters" It appears to me that a small percentage of the Trancas "Geode" thundereggs contain black to white agates sometimes with pink to orange colors. I don't know how rare those kind of agates are since they may be been ignored by the Mexican miners who were looking for hollow geodes or they found a limited quantity. Many Trancas "Geodes" has some rhyolitic shells still attached to them, an evidence that they were formed in the same manner as the thundereggs and that's why I listed those geodes under "Thunderegg" section.

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Rough Appearance: "Rotten coconuts" with brownish thunderegg shells
Most are geodes lined with weird hydrothermal quartz crystals, black to white agates seem to be rare(?)


Some shadowing effect with thunderegg rhyolitc shell	Orange center

Stretched Rhyolitic shell tells me that it's a fully expanded thunderegg.