Cordierite biotite slate hornfels - Wollaston Island
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Fact sheet
Description: 

Darwin wrote "Porphyry; summit of peak. (Crystals larger, fatter, hardly any cleavage, feldspar??)"

Thin reaction rims separate rounded and sometimes sector-zoned cordierite porphyroblasts from the dark irregularly banded slaty matrix of this rock.  Collected Dec 1832 - Feb 1833.

In Place
In Time
Location description: 
Wollaston Island, Tierra del Fuego
Accuracy:
Location precision: 
Moderate
Timescale:
Not known
Ma = Millions of years ago
In Focus
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Type:
Type: 
metamorphic
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