Note 5 - Mineral Rights and Properties (Details Textual) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2021	Apr. 30, 2020
Annual Property Maintenance Fees	$ 2,700		$ 2,700
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=123570139&loc=d3e3602-108585

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