1. Spinels in the groundmass suggest that crustal contamination was extensive. 2. Because their groundmass is generally amorphous in structure, fulgurites are classified as mineraloids. 3. The alkali feldspar is confined to the groundmass . 4. The phlogopites are the glittering minerals surrounded by the green groundmass of olivine . ]] 5. Near the groundmass , which indicates the mounds may have been formed of till originally. 6. The dacites contain phenocrysts of biotite and large feldspar crystals embedded in an oxidized groundmass . 7. "Clavulinopsis " has an free aggulinated test with a considerable calcareous groundmass . 8. The groundmass contains plagioclase, pyroxene, silicon dioxide and oxides of iron and titanium. 9. Resorbed olivine macrocrysts and euhedral primary crystals of groundmass olivine are common but not essential constituents. 10. The primary crystallized and fast crystallized calcites form phenocrysts and fine-grained groundmass , respectively.
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