Conglomeratic obsidian
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Fact sheet
Description: 

Darwin wrote "A most remarkable conglomerate, consisting of mashed bits of porphyritic, jaspery, volcanic rocks, partly embedded in a ferrugineous base, but the whole mixed with patches & thin layers of pitchstone, passing into the nature of obsidian. I should think has certainly flowed as a lava with obsidian. Base of Central Hills. (The glassy rock is some igneous rock allied to the obsidian, partially decomposed, the obsidian greenish black: a concretionary pisolitic structure)"

Collected in July 1836.

In Place
In Time
Location description: 
Ascension Island
Accuracy:
Location precision: 
Poor
Timescale:
Not known
Ma = Millions of years ago
In Focus
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Type:
Type: 
sedimentary
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