Basalt Rubble mound breakwater is one of the most important coastal engineering structures for shore and harbor protection. Rocks can come in all shapes and sizes, is another natural way to stabilize bank and protect from erosion. It can be done with minimal materials and equipment on the beach

General Construction started basalt mining operations at Mats Mats in about 1934; the quarry was one of only two rock quarries on Puget Sound with water access (DNR: Mineral Resources of Washington . Lone Star Northwest bought the quarry in 1995. During the 1990s, as much as 500,000 tons of rock were mined a year, used for road projects, landscaping, preventing erosion , and as harbor breakwaters , seawalls, riprap, bulkheads.