Calcite Mine

Millennia of geological weathering and erosion have cut and polished the landscape into the striking forms you’ll discover while visiting Anza-Borrego’s Calcite Mine area. A highlight of the hike is the mine itself. During World War II, this was an important site — indeed the only site in the United States — for the extraction of optical-grade calcite crystals for use in gunsights. Trench-mining operations throughout the area have left deep scars upon the earth, almost as fresh today as when they were made.

To get to the Calcite Mine, hike from Borrego Springs, follow Highway S-22 (Palm Canyon Drive, Pegleg Road, and Borrego Salton Seaway) east for about 19 miles to a large northside turnout at mile 38.0. That turnout has a view of both the Calcite Mine area to the north and the Salton Sea to the east.

Start your hike by walking 200 yards east along the left side of the highway to the Calcite Mine jeep road intersection, on the left. An interpretive panel here gives some details about the history of the mine. The road has steadily deteriorated over the years; only the toughest of “jeeps” can make it all the way to the mine now. Follow the rough road on foot as it dips into and out of South Fork Palm Wash and continues northwest toward the southern spurs of the Santa Rosa Mountains. Ahead you will see an intricately honeycombed whitish slab of sandstone, called Locomotive Rock, which lies behind (northeast of) the mine area.

About 1.4 miles from S-22, the road dips sharply to cross a deep ravine. Poke into the upper (north) end of this ravine and you’ll discover one of the best slot canyons in Anza-Borrego. (Agile climbers can squeeze through the slot and go up a break on the right side to reach a point above and northwest of the mine area.)

At road’s end, calcite crystals lie strewn about on the ground, glittering in the sunlight. You could spend a lot of time exploring the mining trenches and the pocked slabs of sandstone nearby, including Locomotive Rock itself. Palm Wash, a frightening gash in the earth, precludes travel to the east.

On the return, try this alternate route: Backtrack 0.5 mile to the aforementioned slot ravine. Proceed downstream along its bottom. As you pass through deeper and deeper layers of sandstone strata, the ravine narrows until it allows the passage of only one person at a time. When you reach the jumbled blocks of sandstone in Palm Wash at the bottom of the ravine, turn right, walk 0.3 mile downstream, and exit the canyon via a short link of old jeep trail that leads back to the Calcite Mine road.

This article contains information about a publicly owned recreation or wilderness area. Trails and pathways are not necessarily marked. Conditions can change rapidly. Hikers should be properly equipped and have safety and navigational skills. The Reader and Jerry Schad assume no responsibility for any adverse experience.

Calcite mine
Explore chaotic rock formations and slotlike ravines in Anza-Borrego’s Calcite Mine area.
Distance from downtown San Diego: 112 miles
Hiking length: 4 miles round trip
Difficulty: Moderate