Mine · San Diego County, California, United States

Rosemary's Mountain Quarry

Rosemary's Mountain Quarry is a mine in San Diego County, California, United States, owned by Keeley RMQ LLC; Horizon Hill Materials RMQ LLC.

Facts

Every value links to its source, and to the source's own record where it has one. Licences and last-checked dates are per row.

Fact	Value	Source
Name in the source	ROSEMARY'S MOUNTAIN QUARRY	MSHA Mines Data Set · Public domain · checked 24 Oct 2026
Location	San Diego County	MSHA Mines Data Set · Public domain · checked 24 Oct 2026
Status	Operating (active)	MSHA Mines Data Set · Public domain · checked 24 Oct 2026
Commodities	iron ore (mainly iron ore)	MSHA Mines Data Set · Public domain · checked 24 Oct 2026
Owner	Keeley RMQ LLC; Horizon Hill Materials RMQ LLC (controls the operator)	MSHA Mines Data Set · Public domain · checked 24 Oct 2026
Operator	Horizon Hill Materials, LLC	MSHA Mines Data Set · Public domain · checked 24 Oct 2026
Employees	2 people (annual average, in 2025)	MSHA Mines Data Set · Public domain · checked 24 Oct 2026
Mine type	Surface	MSHA Mines Data Set · Public domain · checked 24 Oct 2026
Coordinates	34.0633, -115.0000	MSHA Mines Data Set · Public domain · checked 24 Oct 2026

Research on this mine and its owner.Who owns it up to the parent company, its permits, resources and offtake, and an introduction to the owner.

Within 50 km of this mine: 4 power plants (1 operating, 501 MW), measured from the coordinates in the facts above. The table shows the nearest 3.

Name	Kind	Size	Status	Distance
McCoy Solar Energy Project Hybrid	Power plant	501 MW	Operating	48 km
Easley Solar	Power plant	940 MW	Under construction	48 km
Vidal Energy Center	Power plant	320 MW	Under construction	49 km

Source: U.S. Energy Information Administration (Sep 2026). EIA-860 / 860M / 923, Public domain.
MSHA Mines Data Set. MSHA Mines Data Set, Public domain.