samples (basalts) exposed (Swann et al. NASA# S71-46632. 15556 is a very vesicular, olivine-normative mare basalt. Basalt Basalt is a mafic extrusive rock, is the most widespread of all igneous rocks, and comprises more than 90% of all volcanic rocks. Vesicular basalt is a dark-colored volcanic rock that contains many small holes, more properly known as vesicles. Volcanic rocks are named according to both their chemical composition and texture. The sample is ~3.4 b.y. The vesicle size varies across the sample (4-8 mm), but the grain size of the minerals doesn’t vary. • Two main groups of Basalts; amygdaloidal and vesicular basalts. If this happens deep underground, they are intrusive igneous rocks. Cube is 1 inch. Basalt is a very common volcanic rock with low silica content. • Vesicular basalt is rich in calcic-plagioclase, augite, olivine and amygdales. Vesicular basalt (3.1 cm across at its widest) Igneous rocks form by the cooling & crystallization of hot, molten rock (magma & lava). It has the appearance of vesicular lava. Vesicular Olivine-normative Basalt . A 15-centimeter (5.9 in) piece of pumice supported by a rolled U.S. $20 bill demonstrates its very low density. High-Ti and Low-Ti basalts have been distinguished in the Paraná and Etendeka traps a nd the Emeishan Traps.. Mid-ocean ridge basalt (MORB) is a tholeiitic basalt commonly erupted only at ocean ridges and is characteristically low in incompatible elements Scoria has more holes and may be black or red in color. • Petrophysical behavior is strongly dependent on degree of oxidation & alteration. These voids are the relics of gas bubbles that were present in lava during solidification of the rock. 1971). Basalt rocks are in some cases classified after their titanium (Ti) content in High-Ti and Low-Ti varieties. Figure 1: Photograph of vesicular basalt 15016. A vesicle is a small cavity in a volcanic rock that was formed by the expansion of a bubble of gas that was trapped inside the lava. Scoria is vesicular and dark colored igneous rock that have or have not contain any crystals. Vesicular basalt occurs naturally in the Salt-Gila Basin at … These samples are all very vesicular; up to 30% (figures 1, 2, 7, 9, 10). It is typically dark color, such as dark brown, black or purplish red. Vesicular basalt is a mafic volcanic rock characterized by several exterior and internal cavities. The top of a lava flow is made up of a highly vesicular, rubbly material known as scoria. The texture is described as “plagioclase-poikilitic” (Neal and Taylor 1993). Vugs extend up to 12 mm. Most scoria is basaltic or andesitic in composition. Because of its relatively low silica content, basalt lava has a comparatively low viscosity, and forms thin flows that can travel long distances. old. Introduction . The term scoria is used for a highly vesicular basalt which is more vesicle and less rock (and so quite lightweight, low density), while vesicular basalt is often used for a sample that is more dense with a smaller fraction of vesicles than rock. High and low titanium basalts. If this happens at or near the land surface, or on the seafloor, they are extrusive igneous rocks. Composition Most Common Minerals Rock Name; felsic: glass (may contain a few minerals typical of felsic rocks) pumice: mafic: glass (may contain a few mineral typical of mafic rocks) scoria: Note: Basalt with fewer holes, known as vesicles, is called vesicular basalt. Due to low trace element content they grouped 71037 with “Type B Apollo 17 basalts”. GLASSY TEXTURE (1977), Rhodes and Hubbard (1973) and Vesicular olivine basalt from La Palma (green phenocrysts are olivine). The variation among such rocks is continuous, so any distinction among categories is arbitrary. Lunar Sample 15016 is a highly-vesicular, olivine­ normative, basalt with a major element composition similar to that of non-vesicular basalt 15555 (figure 1). high-Ti basalt. 923.7. grams . Petrography . Most igneous rocks have a crystalline texture, but some are clastic, vesicular, frothy, or glassy. The petrophysical behaviour & petrographical descriptions of amygdaloidal basalt. McGee et al.