...less siliceous than granite and rhyolite, and contains much more iron, calcium, and magnesium. Bolson (pronounced bowl-sown'). A flat-floored desert valley...crystalline texture. Its principal constituent minerals are feldspar, augite, and usually olivine. Olivine is easily changed by weathering, and in many diabases...

...less siliceous than granite and rhyolite, and contains much more iron, calcium, and magnesium. Bolson (pronounced bowl-sown'). A flat-floored desert valley...crystalline texture. Its principal constituent minerals are feldspar, augite, and usually olivine. Olivine is easily changed by weathering, and in many diabases...

...less siliceous than granite and rhyolite, and contains much more iron, calcium, and magnesium. Bolson (pronounced bowl-sown') . A flat-floored desert valley...crystalline texture. Its principal constituent minerals are feldspar, augite, and usually olivine. Olivine is easily changed by weathering, and in many diabases...

...less siliceous than granite and rhyolite, and contains much more iron, calcium, and magnesium. Bolson (pronounced bowl-sown'). A flat-floored desert valley...crystalline texture. Its principal constituent minerals are feldspar, augite, and usually olivine. Olivine is easily changed by weathering, and in many diabases...

...drains to a central evaporation pan or playa. Bomb. See Volcanic bomb. Breccia (pronounced breU-h'a). A mass of naturally cemented angular rock fragments....crystalline texture. Its principal constituent minerals are feldspar, augite, and usually olivine. Olivine is easily changed by weathering, and in many diabases...

...drains to a central evaporation pan or playa. Bomb. See Volcanic bomb. Breccia (pronounced bretcb/a). A mass of naturally cemented angular rock fragments....crystalline texture. Its principal constituent minerals are feldspar, augite, and usually olivine. Olivine is easily changed by weathering, and in many diabases...

...rock formed from rounded pebbles, usually with more or less sand, mud, etc. A consolidated gravel, Diabase. A heavy, dark, intrusive rock having the...composition as basalt, but on account of its slower cooling, it has a more crystalline texture. It corresponds closely in origin and composition with gabbro, but...

...composed largely or wholly of crystallized material, commonly as the result of metamorphism. (La Forge) Crystalline rock. A rock composed of closely fitting...of sand or other material or with a volcanic glass. (Standard) Crystalline schists. Rocks that have been entirely or partly recrystallized by metamorphism....

...wholly of crystallized material, commonly as the remit of metamorphlsm. (La Forge) Crystalline rook. A rock composed of closely fitting mineral crystals...of sand or other material or with a volcanic glass. (Standard) Crystalline schists. Rocks that have been entirely or partly recrystalllzetl by metamorphlsm....