Granite porphyry (English spelling: granite porphyry)

Japanese: 花コウ斑岩(花崗斑岩) - かこうはんがん（英語表記）granite porphyry

Porphyritic rock of granite composition. Generally seen as a small-scale intrusive body. Used for rocks with prominent phenocrysts of potassium feldspar, plagioclase, quartz, biotite, etc., and embedded in groundmass composed of fine-grained similar minerals. It is difficult to draw a clear line between porphyritic granite and quartz porphyry. Formed when crystallizing granite magma suddenly intrudes near the earth's surface. Famous for its association with porphyry copper deposits, which are important copper resources. [Ishihara Shunzo]

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

花コウ岩組成の斑状岩。一般に小規模な貫入岩体としてみられる。斑晶としてカリ長石，斜長石，石英，黒雲母などが目立ち，かつ細粒の同様鉱物からなる石基に埋められる岩石にたいして用いられる。斑状花コウ岩，石英斑岩との間に明瞭な一線をひきがたい。結晶化しつつある花コウ岩質マグマが急激に地表近くに貫入して生じる。銅資源として重要な斑岩銅鉱床を伴うことで有名である。【石原舜三】

出典　株式会社平凡社世界大百科事典第２版について　情報

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