A lokacin da aka gano su, Koriya ta Arewa ta yi iƙirarin cewa ramin ya kasance don hakar kwal; duk da haka, ba a sami kwal a cikin ramin ba, wanda aka haƙa ta cikin dutsen dutse.
Tabbas, wani nau'i mai rikitarwa na jumla shine "Bayan gano su, Koriya ta Arewa ta yi iƙirarin cewa ramin ramin ya kasance don hakar kwal; duk da haka, ba a sami kwal a cikin ramin ba, wanda aka haƙa ta cikin dutsen granite, amma an fentin wasu bangon ramin baƙar fata don ba da bayyanar anthracite. "