The 26-year-old woman went missing from a mining camp at Lighting Ridge, near the Queensland border, on Friday night.
Her husband reported her missing the next day and a search was launched that afternoon, with temperatures soaring above 40 degrees Celsius.
Inspector David Checkley said they were very concerned for her welfare not only because of the heat but also because the area is covered in opal mine shafts.
"Due to poor light, loss of light in the evening, the search was restricted to vehicle searching, due to the number of mines there and just the dangers associated with the area," Mr Checkley said.
On Sunday morning a line search involving police and personnel from the State Emergency Service and Rural Fire Service was mounted from the camp and a drone used to scan the wider area.
At 10:20am the searchers found the woman eight metres down a mine.
Officers from the Western Region Rescue Unit used a pulley and harness system to bring the woman to the surface.
She suffered abrasions and was taken to Lightning Ridge Hospital in a stable condition.
Police described her as being in reasonable spirits, and despite the heat above ground, conditions in the mine were not bad.
"We were pretty lucky in this situation in that the temperature in the mine shaft was quite low - the temperature there is normally about 22 degrees - so that assisted in this situation," said Inspector Checkley.
"She's actually reported that she was quite cold overnight."
The woman was unlikely to make the same mistake again, he said.
"She's reported that she went for a midnight walk from the camp, which is obviously dangerous in those sorts of area and she's found that out," said Inspector Checkley.
"She's told us that she certainly won't be doing that again."
The area is about 700km north-west of Sydney.
Photo: NSW Police The woman spent two days trapped in a mine in one of NSW's most remote locations.