feldspar

Common feldspar is itself largely used for the same purpose.

The color is due to a large amount of potassium feldspar.

Feldspar is also found in many types of sedimentary rock.

Finally, a temperature is reached when a third mineral, feldspar, joins in.

I turned about and looked at the great rock, the granite streaked with feldspar.

Quartz is the second most common mineral in the world (next to feldspar).

Instead, a very slow cooling rate allowed many large white crystals of feldspar to form.

Below is a description of the different types of feldspar.

It appears light-coloured due to the high proportion of white feldspar.

The alkali feldspar crystals can be up to 18 mm across.

Decay of the feldspar has enabled it to be cut and dressed as a quality building stone.

Commodities such as black granite, corundum, and feldspar are also found.

More recent studies suggest that the blue-green color results from small quantities of lead and water in the feldspar.

It is chiefly derived from the decomposition of common feldspar.

It is quite hard, with hardness 5.5 to 6, close to that of feldspar, and specific gravity 3.6 to 3.8.

Earthenware, which is often made from clay, quartz and feldspar.

The different types of feldspar can be distinguished under a petrographic microscope.

The long axes of the feldspar grains show a preferred orientation in some places.

If feldspar is present, it is in minor volumes or traces.

Tiny crystals of feldspar were embedded in it and sparkled as the sun played on them.

It was almost dusk, but he could see free gold in reddish feldspar porphyry.

The sandstone is made up of quartz and feldspar.

A similar phenomenon takes place also in selective alteration of alkaline feldspar.

Next a stream channel formed over the land, dumping coarse sand with feldspar.

Feldspar or limestone, both prevalent in the area, had the possibility of being highly friable.