The Neoarchaean Kalgoorlie Gold Field contains the giant Golden Mile and world-class Mt Charlotte deposits, which have been the subject of much research for over 100 years.
Stonehenge Stones,the website of Preseli Bluestone Limited, is the only company in the world licensed to extract and supply Preseli Bluestone (the original stone used in the building of Stonehenge) for commercial purposes.
Rockhounding Utah. Utah is an extraordinary state for rockhounding.
Porphyritic – an adjective used to describe igneous rocks that have a distinct difference in the size of the crystals, like the granites from Land's End, St. Austell and Dartmoor.
Detailed description, properties, locality information guide about the potassium feldspar mineral sanidine.
Feldspar definition, any of a group of minerals, principally aluminosilicates of potassium, sodium, and calcium, characterized by two cleavages at nearly right angles: one of the most important constituents of igneous rocks.
Mylonite with large (largest is over 10 cm) K-feldspar porphyroclasts. Sør-Trøndelag, Norway. White plagioclase in norite. Rogaland, Norway. Width of sample 8 cm. Wyborgite is the most classic rapakivi from the type locality in SE Finland.
This diagram shows the main groups of igneous rocks, their main mineral constituents and their intrusive (cooling in the crust) and extrusive (cooling as lava flow) equivalents.
Detailed description, properties, locality information guide about the plagioclase feldspar mineral group: albite to andesine.
Feldspar - Chemical composition: All the rock-forming feldspars are aluminosilicate minerals with the general formula AT4O8 in which A = potassium, sodium, or calcium (Ca); and T = silicon (Si) and aluminum (Al), with a Si:Al ratio ranging from 3:1 to 1:1.
Red Gemstones & Minerals. The following is a list of Red gems and minerals listed in our database. Click the pictures to get full data, click the X to remove the gem from the list.
Sunstone is a plagioclase feldspar, which when viewed from certain directions exhibits a spangled appearance.It has been found in Southern Norway, Sweden and in various United States localities.
The minerals of which the composition is comprised between Albite and Anorthite are known as the plagioclase feldspars, while those comprised between Albite and Orthoclase are called the alkali feldspars due to the presence of alkali metals sodium and potassium.
Feldspar: Feldspar, any of a group of aluminosilicate minerals that contain calcium, sodium, or potassium. Feldspars make up more than half of Earth's crust, and professional literature about them constitutes a large percentage of the literature of mineralogy.
Etymology. The name feldspar derives from the German Feldspat, a compound of the words Feld, "field", and Spat, "a rock that does not contain ore". The change from Spat to -spar was influenced by the English word spar, meaning a non-opaque mineral with good cleavage.