Abstract
Icebergs are hardly colorless monoliths, and even nominally white bergs routinely display many hues.1-3 However, satisfactorily accounting for vivid bottle-green icebergs4-8 has proven to be an elusive goal. Obviously, the colors of some sea and glacier ice are caused by intrinsically colored9 minerals or organisms.10-12 Yet ice recently taken from (or near) green icebergs indicates that they may not be dominated by green inclusions. Amos reported that an unusual ice sample taken near a green iceberg was “remarkably bubble-free” and included "a large number of fibers …ranging from colorless to blue, orange, and green; obsidian flakes; a few quartz grains; amorphous aggregates; black, charcoal-like fragments; pieces of shelly material; and diatoms …."7 Dieckmann et al. sampled a green iceberg in the Weddell Sea, and they found ice containing "grey mineral and biogenic material apparently of marine origin" distributed in “relatively well defined layers" throughout.8 They reached the same tentative conclusion as Amos, holding that: "Our analyses and observations confirm that the green colouration was not caused by green pigmentation, but probably by reflection and/or absorption of light due to the more or less densely spaced, parallel layers of incorporated debris. Green feldspars which could have been responsible for the colour were rarely found. "8 They also note that their ice block "changed from green to a translucent white upon separation from the iceberg. "8 (Gerhard Dieckmann kindly provided me with some original color slides of this green iceberg.)