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2. Feldspar - Wikipedia

   en.wikipedia.org/wiki/Feldspar

   Feldspar (/ ˈfɛl (d) ˌspɑːr / FEL (D)-spar; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. [3] The most common members of the feldspar group are the plagioclase (sodium-calcium) feldspars and the alkali (potassium-sodium ...

3. Pegmatite - Wikipedia

   en.wikipedia.org/wiki/Pegmatite

   Pegmatite. A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than 1 cm (0.4 in) and sometimes greater than 1 meter (3 ft). Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite.

4. Orthoclase - Wikipedia

   en.wikipedia.org/wiki/Orthoclase

   Orthoclase crystal twinning from the Organ Mountains in New Mexico. Orthoclase is a common constituent of most granites and other felsic igneous rocks and often forms huge crystals and masses in pegmatite. Typically, the pure potassium endmember of orthoclase forms a solid solution with albite, the sodium endmember (NaAlSi 3 O 8), of plagioclase.

5. Porphyry (geology) - Wikipedia

   en.wikipedia.org/wiki/Porphyry_(geology)

   Porphyry (geology) Porphyry (/ ˈpɔːrfəri / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate -rich, generally aphanitic matrix or groundmass. In its non-geologic, traditional use, the term porphyry usually refers to the purple-red form of ...

6. Plagioclase - Wikipedia

   en.wikipedia.org/wiki/Plagioclase

   Plagioclase displaying cleavage. (unknown scale) In volcanic rocks, fine-grained plagioclase can display a "microlitic" texture of many small crystals. Plagioclase (/ ˈ p l æ dʒ (i) ə ˌ k l eɪ s, ˈ p l eɪ dʒ-,-ˌ k l eɪ z / PLAJ-(ee)-ə-klayss, PLAYJ-, -⁠klayz) [4] is a series of tectosilicate (framework silicate) minerals within the feldspar group.

7. Amazonite - Wikipedia

   en.wikipedia.org/wiki/Amazonite

   Amazonite, also known as amazonstone, [4] is a green tectosilicate mineral, a variety of the potassium feldspar called microcline. [4][5][6] Its chemical formula is KAlSi 3 O 8, [1][7] which is polymorphic to orthoclase. Its name is taken from that of the Amazon River, from which green stones were formerly obtained, though it is unknown whether ...

8. Sunstone - Wikipedia

   en.wikipedia.org/wiki/Sunstone

   Sunstone. Sunstone is a microcline or oligoclase feldspar, which when viewed from certain directions exhibits a spangled appearance. It has been found in Southern Norway, Sweden, various United States localities and on some beaches along the midcoast of South Australia.

9. Moonstone (gemstone) - Wikipedia

   en.wikipedia.org/wiki/Moonstone_(gemstone)

   Moonstone (gemstone) Moonstone is a sodium potassium aluminium silicate ( (Na,K)AlSi 3 O 8) of the feldspar group that displays a pearly and opalescent schiller. [1][2] An alternative name for moonstone is hecatolite[2] (from goddess Hecate).