There is not much to go on with this story. No word on where it was taken which would give an better indication of the cause of the contrast in ice colors shown.
A black iceberg has made a ton of fans today after a photo of it was posted on Reddit[...]
The darker ice is formed by a higher density of bubble-free ice with a greater amount of rock detritus from the base of the “parent glacier.”
An iceberg is a piece of freshwater ice that has broken off from an ice sheet and is floating free in the water. Because it is less dense than sea water, it floats. The whiteness of the ice is caused by air bubbles. Dark blue ice is denser and has less air trapped in the crystal structure.
Ideas of why this ice is black include: oil contamination, volcanic ash, high density from greater pressure (bottom ice), and discoloration from silt particles. The last one seems the best explanation. It’s dirty ice. But watch for it to be linked to an oil spill and used as environmental propaganda. Beware of the speculated explanations.
Any additional information on this is appreciated.
Addition: We got some confirmation from polar oceanographer Mark Brandon
— Mark Brandon (@icey_mark) January 6, 2013
Absolutely gorgeous striped ice can be seen here.