Embleton Diorite

 

In Alan Smith's book "Lakeland Rocks" page 120 he mentions a quarry that turned out to be huge. He says that the rock was mistakenly called "Embleton Granite" but is really a diorite. Yes, it has the larger crystals that show that it cooled more slowly being underground, compared to the lavas that cool quickly in the open air. But its chemical composition is the same as andesite, an intermediate rock between the basic basalt lavas and the rhyolites. There is a lot of plagioclase feldspar in it - feldspar with more calcium in it - and so not pink like the potassium-rich orthoclase feldspars. There were gold crystals in some samples which we think must be iron pyrites.