Complex sentence: Gold-bearing ore was recovered from two groups of quartz veins about a thousand feet apart, to tap these six tunnels were bored, two of them reaching back 425 feet into the Mountainside.
Split into simpler sentences: Gold-bearing ore was recovered from two groups of quartz veins about a thousand feet apart. To tap these six tunnels were bored, two of them reaching back 425 feet into the mountainside.