Sjögruvan

Sjögruvan – ”Nya Krakboförsöket” Sjögruvan, also known as Nya Krakboförsöket, was only worked during the years 1863–1865. The work initially appeared very promising. Once the shaft had reached a depth considered safe enough to begin driving levels, the ore could be followed:

• towards the southeast (SE), in the direction of the lake
• towards the northwest (NW)

The deposit, however, diminished rapidly with depth and was already considered barely worth mining by the end of 1864. By 1865 the mine was virtually barren and work ceased.

Dimensions

• Depth: approx. 15 metres
• Length: approx. 12.5 metres
• Width: approx. 2.5 metres

Transcript from the Records of the Mines of Filipstad’s Bergslag

Year 1863 Just north of the outlet of the Tilas adit, very close to the lake shore and the ore wharf filled in there, a compass bearing had been known for several years. The proximity to the lake shore had previously been considered to have prevented mining.

During the summer of 1863, work was taken down to the bedrock and a fine ore was found. A timber casing was arranged and lowered in order to exclude the water pressing in from the ore wharf immediately to the east, which had been filled in with waste rock.

The work was considered very promising.

Year 1864 After the timber casing had been carefully sealed against the rock, work continued by sinking. The ore appeared to widen, particularly towards the south.

Once the sinking had progressed far enough into solid rock that driving a level towards the SE could be ventured, the ore was followed with a drift. It proved to increase somewhat during the sinking. The ore also continued somewhat towards the NW.

After 5–6 months, an ore bottom of the following dimensions had been established:

• 6–7 fathoms in length
• 1–1½ fathoms in width

The deposit diminished during continued sinking, however, and by year’s end was barely worth mining. The ore also thinned in both ends, which meant that field-level driving had to cease.

During the year, 19,610 centner (Ctr) of ore were obtained.

Year 1865 The ore continued to diminish, both laterally and with depth. When the bottom had become almost barren, work was concluded.

During the year, a further 6,000 Ctr of ore were obtained.

Units of Measurement

• 1 Centner (Ctr) = 42.5 kg
• 1 Fathom = 1.78 metres