There are several online sources telling the reader that Shilajit - Mumijo is usually contaminated with heavy metals (a warning which is usually combined with a 'better' offer - LOL).
Such statements are easy to counter though - have the product tested by an independant laboratory and share the results online. The biggest critic might be the Natural News website ('Health Ranger' Mike Adams) which is why we choose their laboratory to test our product. The outcome was excellent.
On this website you can find a lot of objective background including an overview of over 25 Shilajit resins as sold on Amazon and other platforms, comparing price, test results and reliability.