When.com Web Search

Search results

  1. Results From The WOW.Com Content Network
  2. 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.

  3. Albite - Wikipedia

    en.wikipedia.org/wiki/Albite

    Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. It represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula Na Al Si 3 O 8. It is a tectosilicate. Its color is usually pure white, hence its name from Latin, albus. [5]

  4. Feldspar - Wikipedia

    en.wikipedia.org/wiki/Feldspar

    Feldspar (/ ˈ f ɛ l (d) ˌ s p ɑːr / 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 ...

  5. QAPF diagram - Wikipedia

    en.wikipedia.org/wiki/QAPF_diagram

    QAPF diagram for classification of plutonic rocks. A QAPF diagram is a doubled-triangle plot diagram used to classify intrusive igneous rocks based on their mineralogy.The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)", which are the four mineral groups used for classification in a QAPF diagram.

  6. Anorthite - Wikipedia

    en.wikipedia.org/wiki/Anorthite

    Anorthite is the calcium-rich endmember of the plagioclase solid solution series, the other endmember being albite (NaAlSi 3 O 8). Anorthite also refers to plagioclase compositions with more than 90 molecular percent of the anorthite endmember.

  7. Orthoclase - Wikipedia

    en.wikipedia.org/wiki/Orthoclase

    Typically, the pure potassium endmember of orthoclase forms a solid solution with albite, the sodium endmember (NaAlSi 3 O 8), of plagioclase. While slowly cooling within the earth, sodium-rich albite lamellae form by exsolution, enriching the remaining orthoclase with potassium. The resulting intergrowth of the two feldspars is called perthite.

  8. Anorthosite - Wikipedia

    en.wikipedia.org/wiki/Anorthosite

    The feldspar variety labradorite is commonly present in anorthosites. Mineralogically, labradorite is a compositional term for any calcium-rich plagioclase feldspar containing 50–70 molecular percent anorthite (An 50–70), regardless of whether it shows labradorescence.

  9. Silicate mineral - Wikipedia

    en.wikipedia.org/wiki/Silicate_mineral

    Tectosilicates, feldspar group Alkali feldspars (potassium feldspars) ... Plagioclase feldspars Albite – NaAlSi 3 O 8; Oligoclase – (Na,Ca)(Si,Al) 4 O 8 (Na:Ca 4:1)