Siderophyllite Granite - Luxulyan 1 (#10)
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Fact sheet
Description: 

This sample of siderophyllite(biotite)-rich granite comes from Luxulyan (Tregarden) quarry to the north of Luxulyan village. This sample is a less evolved portion of the intrusion, which is associated with later the tourmaline and topaz-rich intrusions and mineralisation. Luxulyan valley is part of a World Heritage Site containing the remains of extensive early 19th century industrial activity, including mining and quarrying, which at its peak included several water wheels and steam engines.

The thin section illustrates the quartz-rich nature of the rock, which also contains altered orthoclase, plagioclase and both siderophyllite and muscovite. The siderophyllite is notably rich in pleochroic haloes, indicating a high proportion of zircon and monazite crystals. Rotation 1 displays a rare crystal of cordierite surrounded by typical pinite alteration.

In Place
In Time
Location description: 
Luxulyan quarry, near Luxulyan, St Austell, Cornwall
Accuracy:
Location precision: 
Good
Timescale:
Timescale: 
Permian
Ma = Millions of years ago
In Focus
Collection:
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Type:
Type: 
igneous
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Accessory minerals:

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