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SGI’s Charmian Plant has existed as a mining operation to support the roofing industry for 100 years. While SGI did not own the site for the entirety of its history, the company recently marked the Charmian Plant’s centennial milestone, paying homage to the significance it has played in manufacturing high-quality roofing products since 1923.

“The site had conducted mining operations even earlier, but the material mined was used for other purposes,” explained SGI President Justin P. Dunlap. “It wasn’t until 1923 that the site began mining the rock there specifically for roofing.”

Mining activities at the site are believed to have started as early as the late 1800s. The rock mined at the Charmian Plant today is estimated to be around 820 million years old – formed by volcanic activity during major geologic events that occurred over disruptive periods of the earth’s history.

When the site began mining to produce roofing granules in 1923, the granules were left uncolored. By 1930, though, the Charmian Plant started to produce colored roofing granules.

“Over the years, and specifically in the last two decades, roofing granules have evolved through intentional innovation to include a variety of colors, blends, and reflectivity.”

Today, SGI mines rock at the site for roofing products, building materials and soil amendments used in agriculture.

“Our most recent and exciting development is the discovery that the undersized material mined at our Charmian Plant has beneficial use in agriculture,” said Dunlap. “Not only does the material improve nutrient availability in the soil for growing plants, but after years of academic studies, we can confirm that the material removes carbon from the atmosphere.

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