Igneous Rocks

5. gray, fine grained igneous rock, primarily of volcanic origin and commonly exhibiting a porphyritic texture
8. texture an igneous rock texture consisting of large crystals embedded in a matrix of much smaller crystals
9. composition compositional group of igneous rocks that indicates a rock is composed almost entirely of light colored silicates
10. texture term applied to igneous rocks that contain small cavities called vesicles, which are formed when gases escape from lava
12. light colored, glassy vesicular rock commonly having a granitic composition
14. texture term used to describe the texture of certain igneous rocks, such as obsidian, that contains no crystals
16. composition compositional group of igneous rocks indicating that the rock contains substantial dark silicate minerals and calcium-rich plagioclase feldspar
17. an abundant, coarse grained igneous rock, composed of about 10 to 20 percent quartz and 50 percent potassium feldspar
18. magma that reaches earths surface
19. rock igneous rock formed when magma solidifies at earth's surface
22. a dark green to black intrusive igneous rock composed of dark silicate minerals
24. rock igneous rock that formed below earth's surface.

1. (intermediate) composition compositional group of igneous rocks that contains at least 25 percent dark silicate minerals
2. fine grained igneous rock of magic composition
3. grained texture texture of igneous rocks in which the crystals are too small for individual minerals to be distinguished with the unaided eye
4. in an igneous rock with a porphyritic texture, a conspicuously large crystal embedded in a matrix of finer grained crystals called the groundmass
6. size, shape, and distribution of the particles that collectively constitute a rock
7. fragmental texture an igneous rock texture resulting from the consolidation of individual rock fragments that are ejected during a violent volcanic eruption
11. the fine grained equivalent of the igneous rock granite
13. body of molten rock found at depth
15. grained texture an igneous rock texture in which the crystals are roughly equal in size and large enough that individual minerals can be identified with the unaided eye
16. differentiation the process of generating more than one rock type from a single magma
20. a volcanic glass of Felsic composition
21. reaction series a concept proposed by N. L. Bowen that illustrates the relationship between magma and the minerals crystallizing from it during the formation of igneous rocks
23. settling during the crystallization of magma, the settling of the earlier formed minerals that are denser than the liquid portion to the bottom of the magma chamber