| 释义 |
porphyroidenUK
por·phy·roid P0452300 (pôr′fə-roid′)n. Metamorphic rock having porphyritic texture.porphyroid (ˈpɔːfɪˌrɔɪd) adj (Geological Science) (of metamorphic rocks) having a texture characterized by large crystals set in a finer groundmassn (Geological Science) a metamorphic rock having this texture
PorphyroidenUK
porphyroid[′pȯr·fə‚rȯid] (petrology) A blastoporphyritic, or sometimes porphyroblastic, metamorphic rock of igneous origin. A feldspathic metasedimentary rock having the appearance of a porphyry. Porphyroid (also porphyritoid), a rock formed as a result of the metamorphism of rocks with similar composition, such as diabases, porphyrites, or gangues. Porphyroid is usually composed of feldspar, amphibole, pyroxene relicts, calcite, chlorite, talc, and clay; sometimes it contains quartz and zoisite. As a result of strong cataclasis, porphyroid sometimes takes on a slaty texture. |