Dyke and quartz porphyry

Dyke and quartz porphyry - You have seen quartz veins before. Here you will see some similar structures but on a larger scale. A dyke is a vertical intrusion of once molten material into a fracture, but the dimensions of dykes are much more extensive than veins. Subsequent weathering and other processes expose the cross section of this interesting feature you see today. The intrusive material in this dyke is quartz porphyry. Since weathering has been very intense in this area, its colour has become darkened. Do you know which type of rock quartz porphyry belongs to?