These are the best valued rings for mining sources, as well as bounty hunting. You should not mine in ring systems which are depleted, low, common or even major reserves, always go for pristine reserves as that gives you the best minerals.
Also strangely this has direct affect on how large bounties your get from killing wanted ships in RES.
Snake Confirmed Pristine Metallic:
20 Ophiuchi
38 Lyncis
58 Epsilon Herculis
Alkupai (medium landing pad, ie outpost)
Atins
Basuki An
Bhare
Bhotho
Bhumliaurt
Chamas (distance from star must be like 14,000ls)
Delkar
Frey
Gcrv 1568
Gendenwitha
Harma
Hip 104504
Hip 104549
Hip 105408
Hip 17272
Hip 19934
Hip 21991
Hip 33368
Hip 4005
Hip 61061
Hip 61632
Hip 8865
Hip 93377
Hr 1385 (medium landing pad, ie outpost)
Hr 4720
Hr 5307
Kehperi
Lalande 34968
Latugara
Moyot
Njikan
Omicron Capricorni B
Omicron Ursae Majoris
Paesia
Phraces
Polahukuna
Salikians
Sang Wana
Sawahinn
Tehuevi
Tofana
Umaitis
Wolf 1458
Snake Confirmed but no detailed scan, so ring type (metallic, metal rich, icy etc) is unknown:
Algol (no station)
Hr 8461 (medium landing pad, ie outpost)
System map unavailable (not explored):
60 Herculis
Bajauie (most likely asteroid belt bullshit)
Bd-08 2963
Gcrv 4259 (most likely asteroid belt bullshit)
Genetrix
Hip 51652
Hip 60230
Hip 7799
Quikinnaqu (most likely asteroid belt bullshit)
A Lavigny-Duval Control Systems (gives 20% passive bonus on bounties):
Hip 16607
Jura
Snake Confirmed Pristine Metal Rich:
Hip 77818
Hip 35246
Unconfirmed:
HIP 13257 BC 3 A Ring
Phra Narai A Belt
FEHU
Bhaga 7 A ring