Activist group Friends of the Earth is urging Apple to come forward and own up to the use of Bangka tin in its products - the mining of which is wreaking havoc in Indonesia, killing coral, and destroying tropical forests.
Tin can be found in every phone, FotE claims, and is essential as a solder. A third of the world's tin is harvested from Bangka and nearby Beitung.
An investigation by FotE has found the tin mining in Bangka is dangerous and unregulated and is directly harming local people by harming crop growth. Soil, FotE says, has been turned acidic following the clearing of forests for tin mining.
Silt, meanwhile, is polluted by tin mining and killing coral reefs and seagrass. This drives away fish, an important food source for locals.
Although Apple, with Philips and Samsung, has signed up to a partnership with Dutch government agency the Sustainable Trade Initiative, and the Electronics Industry Citizenship Coalition, to discuss the problems of mining Bangka tin, it is refusing to come clean, in line with the apparent modus operandi at Cupertino with other controversies.
"Unlike Samsung, Apple is still keeping its customers in the dark by refusing to confirm or deny where the tin in iPhones and iPads is from," FotE campaigns director Craig Bennett said in a statement.
"CEO Tim Cook has said he wants to be more transparent about Apple's supply chains - it's time to show he means this by coming clean about Bangka tin," he said.
An open letter from Friends of the Earth to Tim Cook asks the Apple CEO to clarify, when asked Apple's position on whether or not the company sources its tin from Bangka, whether he intends to:
"A) Confirm it, and set out what steps the company is taking to deal with the matter,
"B) Deny it, or
"C) Refuse to be straightforward about your company's supply chain, and continue the current unacceptable practice of refusing to comment".
Apple may be forced to comment if the questions are pressed enough by the public.