Igneous Rock Features List
Click on a feature name to view an information page with images for that feature. The features collection is under construction, so only the highlighted (tan) names have images so far.
- Igneous Rock Only Features
- cross-cutting relationships (e.g. dike, xenoliths)
- elipsoidal holes (vesicles)
- glass
- other volcanic features (e.g. lava flow, spatter cone, etc.)
- pillow structures
- certain minerals (e.g. sanidine, leucite, pigeonite)
- xenoliths
- Igneous Rock Shared Features
- mosaic texture: Ign and Met (grains not rounded, crystalized in place)
- euhedral minerals: Ign and Met (crystal forms visible)
- absence of layering : Ign and Met (metamorphosed igneous rock)
- random orientation of grains : Ign and Sed (not aligned)
- garnet present: Met and Ign
- angular grains in matrix: Ign (pyroclastic), Sed (immature), Met (cataclastic)
- presence of layering: Ign (lava flows, pyroclastic rocks), Sed (bedding), Met (metamophosed layered rock)
- Features Igneous Rocks Do Not Have
- ductile deformation
- consistenly aligned mineral grains (foliation)
- rounded grains
- fossils or trace fossils
- other sedimentary rock features (e.g. cross-bedding, ripple marks)
- carbonate mineral-rich (except carbonatites, which are rare)
- mica-rich (schist)
- gneissic banding
- certain minerals present (e.g. staurolite, chloritoid)
