The outside of the porch is built of a coarse to very coarse (1 mm) local Carboniferous 340 million year old sandstone. You can see the individual quartz (SiO2) grains up to 2 cm with a hand lens. Graded bedding can also be seen: the grain sizes are not all the same, they are a range.
Very coarse carboniferous sandstone
Inside the porch
The porch itself is constructed from local sandstone but this one is medium grained (375μm). The regular marks on the columns are stonemason’s tool marks and have been artistically used to decorate the cut stone. The medium sandstone is easier to work than the coarser material so has been sculptured into flowers.
Medium grained sandstone
Mica flakes in sandstone
The northern windowsill shows the micaceous nature of the sandstone used and the individual muscovite mica (KAl2(AlSi3)10)(OH,F)2) flakes glisten in the sun. Mica, a hydrated sheet silicate, is a mineral which is clearly defined scientifically as naturally occurring, inorganic, crystalline solid with a defined chemical range. This is different to a rock which is defined merely as an agglomeration of minerals. So a rock can be made of one or more minerals.