The Hobson's Horsefly hydraulic pit is located on the Horsefly River, approximately 8 kilometres north of Horsefly and adjacent to the Horsefly - Likely road. The road is marked “Mitchell Bay Road” at the north end of Horsefly. The Augustine ranch covers a substantial portion of the property.

The first placer mining in the Quesnel mining district was along the Quesnel River, and on Horsefly River in 1859. In 1860, new discoveries were rapidly made - Keithley, Snowshoe, and Harvey creeks were discovered and a large amount of gold was produced before the earliest production was recorded in 1874. Fully one-third of the total production of the Quesnel district is believed to have been mined between 1860 and 1873 (Bulletin 28).

Although the main workings are on the west bank, minor work was also done on the east bank. The occurrence is an unusual placer deposit; the auriferous gravels are in a calcite-cemented conglomerate that overlies Eocene lacustrine (shale and siltstone) sediments. The cemented horizon varies from 60 centimetres to 3 metres thick with an average of 2.4 metres. The cemented gravel horizon is continuous and extensive and has been identified over 8 kilometres in a southerly direction to the Wards' Horsefly (093A 015) and Miocene (093A 014) placer workings. The pay gravels are predominantly composed of bull quartz, but small fragments of black shales are also present. The gold was fine to coarse and was frequently found attached to black shale fragments, indicative of a probable source in the mountains at the head of the Horsefly River. Some gold has been produced from "blue shales" at the base of the cemented conglomerate. Above the conglomerate are boulder gravels and finer loose sediments. These contain a very small quantity of gold, enough to make hydraulic mining marginally profitable in the late 1800s. Mr. J.B. Hobson, also manager of the Bullion Pit (093A 025) - Cariboo Hydraulic Mining Co., developed extensive underground workings. A 365-metre main adit connected 1643 metres of crosscuts, gangways and raises in the cemented gravels. The period of underground work was greatest in 1897 and 1898. The majority of significant hydraulic work was done between 1892 and 1899, all under J.B. Hobson and the Horsefly Hydraulic Mining Co.

Recorded production for 1894 to 1899 and 1912 was 238,653 grams of gold. The grade from 2 years of production (1897 and 1898) was 8931 tonnes grading 2.94 grams per tonne gold (Minister of Mines Annual Report 1902).

Total production from Horsefly River between 1876 to 1945 amounted to 473,217 grams gold (Bulletin 28).

Data from the Cariboo mining district indicate that supergene leaching of gold dispersed within massive sulphides by Tertiary deep weathering followed by Cenozoic erosion is the most likely explanation for the occurrence of coarse gold nuggets in Quaternary sediments (Exploration in British Columbia 1989, page 147).

The property was explored in the early 1980s by Shell Canada Resources Ltd. with the objective of proving a paleoplacer deposit. In the late 1980s, the underground workings were opened by a company that held the mine under an option. This company employed Canadian Gravity Recovery Inc. to sample the workings. The sampling results included potentially commercial grades, suggesting that the underground workings be carefully sampled in more detail. In 1998, J.D. Graham (co-owner of the claims covering the workings) traveled to the mine with the intention of sampling the walls of the underground openings but the portal was found to be caved and it could not be reopened with the program funds available. However, several limited exposures of the basal section of the gravels were accessible near the portal timbering and these sections were sampled. In 2006, a geological and physical study was conducted on behalf of owners J.D. Graham and J.M. Ashton. Several samples taken from the pit walls were panned but no significant gold was found; the auriferous horizon is at or below the level of the gravels exposed in the pit walls. The auriferous horizon is essentially only exposed in the underground workings and the caved adit must be opened up in order to test them.