Given the question: I know that the answer to the question "What can copper form into?" is in "Chromobacterium violaceum and Pseudomonas fluorescens can both mobilize solid copper, as a cyanide compound. The ericoid mycorrhizal fungi associated with Calluna, Erica and Vaccinium can grow in copper metalliferous soils. The ectomycorrhizal fungus Suillus luteus protects young pine trees from copper toxicity. A sample of the fungus Aspergillus niger was found growing from gold mining solution; and was found to contain cyano metal complexes; such as gold, silver, copper iron and zinc. The fungus also plays a role in the solubilization of heavy metal sulfides.". Can you tell me what it is?
The answer is:
cyanide compound