Brimstone and its one-stop process for making cleaner cement and critical minerals

Brimstone is a US-based startup founded in 2019 and headquartered in Oakland, California, that tackles two major industrial challenges simultaneously: reducing greenhouse gas emissions from cement production and increasing the domestic supply of critical minerals. The company’s process uses silicate rocks instead of traditional limestone to produce cement, which cuts carbon dioxide emissions by about 60% compared to conventional methods. This is significant because cement manufacturing is responsible for roughly 8% of global carbon dioxide pollution. Additionally, Brimstone’s technology can extract valuable materials like smelter-grade alumina (a key ingredient for aluminum production), steel, magnesium, and titanium from the same silicate rocks, creating a one-stop refining process. This dual approach allows Brimstone to adapt its messaging based on the political climate, emphasizing emissions reduction during climate-focused administrations or domestic mineral production during more protectionist periods.

The traditional process for making cement relies on heating limestone, a type of rock, to very high temperatures. This chemical reaction releases carbon dioxide (CO₂) as a byproduct, contributing significantly to global greenhouse gas emissions. Cement is the binding agent used in concrete, one of the most widely used construction materials worldwide. Because of its ubiquity, the cement industry accounts for about 8% of the world’s carbon dioxide pollution, making it a major target for climate action. Brimstone’s innovation replaces limestone with silicate rocks, which do not release CO₂ during heating. In 2023, the company achieved industry certification for its cement-making process, allowing its product to be used in standard construction projects. This certification is a key step toward commercial viability and wider adoption of its cleaner cement technology.

Critical minerals are metals and other materials essential for modern industries but often difficult to extract or refine, particularly in the United States. Many of these minerals, such as alumina (used in aluminum production), steel, magnesium, titanium, and others, are currently produced primarily in China, which the US government has criticized for its trade policies. Brimstone’s process can extract multiple critical minerals from the same silicate rocks used for cement, potentially reducing the energy, pollution, and costs associated with traditional mining and refining methods. The company’s CEO, Cody Finke, estimates that these materials represent a global market worth $2.4 trillion. By producing these minerals domestically, Brimstone aims to bolster US national security and reduce reliance on foreign supply chains, especially during periods of trade tensions.

Brimstone’s ability to pivot its messaging based on the political climate in the US is a key part of its strategy. During the Biden administration, which prioritized climate action, the company emphasized its ability to produce low-emission cement. However, under the Trump administration, which focused more on protectionism and climate skepticism, Brimstone shifted its emphasis to the domestic production of critical minerals. This adaptability allows the company to align with the priorities of whichever political party is in power, increasing its chances of securing government support, grants, or favorable policies. In 2025, the company highlighted its ability to produce smelter-grade alumina, further demonstrating its versatility in addressing different industrial and political needs.

Brimstone has made progress in securing commercial deals, including agreements to supply cement to Amazon and alumina to Century Aluminum, one of the largest aluminum producers in the US. However, the company has not yet operated at a commercial scale and faces significant financial and technical hurdles. Some industry observers question whether Brimstone can economically extract sufficient quantities of multiple materials from a single type of rock or overcome the high costs and labor challenges associated with mining and refining in the US. In 2024, the Trump administration revoked a $189 million grant intended to fund a commercial demonstration plant in Reno, Nevada, though Brimstone continues to negotiate for its restoration. The company plans to begin operating the Reno facility, which will produce cement, supplementary materials, and alumina, in 2028, with a full-scale factory for other critical minerals likely delayed until the next decade.