Also found in: Thesaurus, Encyclopedia, Wikipedia.
Related to plagioclase: Potassium feldspar, pyroxene, biotite


(Minerals) a series of feldspar minerals consisting of a mixture of sodium and calcium aluminium silicates in triclinic crystalline form: includes albite, oligoclase, and labradorite
plagioclastic adj


(ˈpleɪ dʒi əˌkleɪs)

any of the feldspar minerals varying in composition from albite, NaAlSi3O8, to anorthite, CaAl2Si2O8.
pla`gi•o•clas′tic (-ˈklæs tɪk) adj.


Any of a series of common feldspar minerals, consisting of mixtures of sodium and calcium aluminum silicates. Plagioclase is typically white, yellow, or reddish-gray, but it can also be blue to black. It is especially common in igneous rocks.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.plagioclase - any of a series of triclinic feldspars that form rocks
dacite - a grey volcanic rock containing plagioclase and quartz and other crystalline minerals
basalt - the commonest type of solidified lava; a dense dark grey fine-grained igneous rock that is composed chiefly of plagioclase feldspar and pyroxene
feldspar, felspar - any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium
albite, white feldspar - a widely distributed feldspar that forms rocks
anorthite - rare plagioclastic feldspar occurring in many igneous rocks
References in periodicals archive ?
Plagioclase phenocrysts (29%) show a poorly developed sieved texture and zoning, some are arranged as radiated laths showing incipient variolitic texture (Figs.
This mineral - plagioclase - is the primary mineral found in Moon's crust.
As expected from the literature (GILL, 2015), plagioclase was the most abundant (greatest peak in Figure 1) and among the most soluble minerals in the RM (RAMOS et al.
Further, the petrographic description of the intrusive and metamorphic units describes a widespread weak-to-moderate early and hot potassic alteration, expressed as biotite and K-spar alteration of mafic minerals and K-spar alteration of plagioclase feldspars.
In some cases, they show a crenulated structure or weak to intense deformation superimposed to the main foliation of the rock, developing a mylonitic structure characterized by the presence of thin strips of elongated quartz and actinolite, intercalated with thick bands of quartz and plagioclase.
The body is occupied by petrographically uniform granite composed of perthite, albitic plagioclase, quartz, and small quantities of biotite, opaque oxide and titanite.
Quartz, Plagioclase feldspars and K- feldspars showed their presence in studied samples by petrographic study (Table 2 and Figure 2).
Y fformiwla am y ffeldspar anorthite yw CaAl2Si2O8 a chynhwysa hwn ganran uchel o galch a pherthynai i'r grwp plagioclase o ffeldspar.
2006; Modjarrad, 2015a), and several studies have focused on plagioclase nucleation and growth rate (e.
This pattern of alkalinity can be explained by increasing amounts of plagioclase feldspar fractionation in an alkali basalt parent magma (Frost and Frost 2008; Estrade et al.