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Porphyry

Porphyry is a general name for igneous rocks that contain phenocrysts, especially if the phenocryst mineral is also found in the smaller crystals of the groundmass. It is most often used for rocks with a fine to medium-grained groundmass, that have formed in minor intrusions or lava flows. The term Porphyry is often prefixed.
This can be a reference to the minerals it contains, such as quartz-feldspar-porphyry, which contains those two minerals as phenocrysts.
Alternatively, it can refer to the composition, such as rhyolite porphyry, or texture, such as rhomb porphyry. The latter contains feldspars with rhombic cross-sections.

Porphyry - 3g to 9g Tumbled Stone (Selected)

£ 3.50
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Porphyry - 3g to 9g Tumbled Stone (Selected)