Title: Two Efforts to Dig Test Pits
Source: Minnesota Historical Society
Description: These log entries describe two efforts to dig test pits in search of iron ore.
A record of day-by-day activities.
A. A typical case without difficulties and delays. 168 feet advance in 14 shifts. Three-men crew working day shift only during month of February.
Lining that prevents the hole from caving in.
1 day to move and set up.
1 day to pass through 21 feet of surface.
3 days to sample 55 feet of ore.
1 day to sample 12 feet of ore and taconite.
7 days to pass through 80 feet of taconite.
1 day to pull casing.
34 IRON MINING IN MINNESOTA
Log B. Presents the other extreme. A very bad hole giving much trouble. 307 feet in 187 shifts.
2 days moving, setting up, pipe line, etc.
25 days to pass through 148 feet of surface, progress from 6 inches to 17 feet daily.
20 days to pass through 85 feet of taconite with diamond drill.
2 days blasting diamond drill hole and getting casing down from 148 to 166 feet.
9 days blasting diamond drill hole and getting casing down from 166 to 170 feet.
14 days blasting diamond drill hole and getting casing down from 170 to 187 feet.
14 days casings finally pulled out and hole re-cased.
18 days casings down 197 feet to 237 feet.
60 days consumed in attempts to case down. The casing was wrecked and pulled out and the hole was re-cased 5 times before the ore was finally reached at a depth of 257 feet.
6 days passing through 17 feet of ore.
6 days passing through 37 feet of ore into quartizite.
Total time consumed 187 shifts.