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This andesite is so packed with plagioclase and hornblende phenocrysts that it almost looks coarse-grained. A close look (photo below) reveals a fine-grained gray groundmass surrounding the phenocrysts.
The orangish coloring on some of the grains is iron staining.
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The black phenocrysts are hornblende, the white crystals are plagioclase. The grayish areas between the phenocrysts display some tiny mineral crystals but are mostly too fine-grained to see any crystal grains.
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This andesite has a large black hornblende phenocryst and a large dark grayish blob in the center. The blurry boundary between the blob and surrounding andesite suggests that it may have been a drop of more mafic magma injected into the magma chamber just prior to eruption (or it would have assimilated). This injection may have triggered the eruption that ejected this andesite!
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This sample has been handled by too many dirty hands: the gray is turning brownish and greasy. Yum. Nevertheless, you can still see the black hornblende crystals set against the fine-grained gray groundmass.
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This is another andesite like the one above: gray groundmass with black hornblendes.
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