Note 4 - Mineral Rights and Properties (Details Textual) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Annual Property Maintenance Fees	$ 2,200		$ 2,200
Palangana Mine [Member]
Depletion, Total	$ 0	$ 0	$ 0	$ 0

The noncash expense charged against earnings to recognize the consumption of natural resources.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Name:	us-gaap_Depletion
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration