CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Dec. 31, 2016
Net revenues $ 0 $ 0 $ 0 $ 0 $ 0 $ 0
Operating expenses:            
Compensation and related taxes 769,279 1,237,618 1,647,691 2,312,510 4,797,984 5,337,910
Exploration cost 1,609,982 230,851 2,862,923 828,130 1,219,608 3,913,699
Consulting fees 883,501 699,859 1,678,286 1,222,405 2,418,726 2,289,394
General and administrative expenses 977,310 1,116,564 2,080,997 2,242,477 4,287,909 4,091,967
Total operating expenses 4,240,072 3,284,892 8,269,897 6,605,522 12,724,227 15,632,970
Loss from operations (4,240,072) (3,284,892) (8,269,897) (6,605,522) (12,724,227) (15,632,970)
Other income (expenses):            
Other income 0 9,673 0 9,673 9,673 0
Foreign currency gain (loss) (434) 500 (1,531) (10,655) (10,029) 0
Interest expense and other finance costs (2,660) (2,056) (6,160) (4,978) (380,987) (5,406)
Interest income 6,808 3,141 12,640 4,109 11,069 2,801
Total other income (expenses) - net 3,714 11,258 4,949 (1,851) (370,274) (2,605)
Loss before provision for income taxes (4,236,358) (3,273,634) (8,264,948) (6,607,373) (13,094,501) (15,635,575)
Provision for income taxes 0 0 0 0 0 0
Net loss $ (4,236,358) $ (3,273,634) (8,264,948) (6,607,373) (13,094,501) (15,635,575)
Preferred deemed dividend         (1,068,624) (3,599,565)
Net loss available to common stockholders     $ (8,264,948) $ (6,607,373) $ (14,163,125) $ (19,235,140)
Net loss per common share, basic and diluted (in dollars per share) $ (0.13) $ (0.12) $ (0.25) $ (0.23) $ (0.50) $ (0.75)
Weighted average common shares outstanding - basic and diluted (in shares) 33,629,260 28,400,084 33,603,861 28,394,151 28,567,344 25,483,353