Rio Tinto is testing the market for one of the quiet pillars of its portfolio: its U.S. boron operations in California, which supply roughly 30% of global refined borates and have now drawn interest from more than a dozen potential bidders. According to Bloomberg and Reuters, the assets – which could fetch up to 2 billion dollars – sit at the heart of CEO Simon Trott’s push to raise 5–10 billion dollars through divestments and productivity gains, freeing up capital to focus the group on iron ore, copper, aluminium and lithium while trimming group capex and simplifying the mine mix.
The package on the block includes the century‑old Boron mine in the Mojave Desert town that literally bears the element’s name, still the world’s largest borax operation, along with processing plants, a refinery and export terminal at the Port of Los Angeles, and the Owens Lake mining operation near the Sierra Nevada. Geology is part of the appeal: estimates suggest reserves that can sustain output into the early 2040s, giving chemical producers and private‑equity buyers not just scale but a long‑duration position in a mineral that the U.S. has reclassified as “critical” for everything from fertilizers and heat‑resistant glass to renewable‑energy hardware and even nuclear applications.
What exactly is Rio Tinto $RIO selling
According to reports from Bloomberg, Mining.com and other sources, Rio Tinto is looking to sell the entire package of its pine operations in California. This includes:
An open pit mine and processing facility in the Mojave Desert town of Boron, the world's largest borax mine
a refinery and shipping terminal at the Port of Los Angeles
mining at Owens Lake near Sierra Nevada
These operations, according to company and analyst data, account for approximately 30-33% of global demand for refined boron and borates, making them literally the backbone of the global market for this critical mineral. Sources cited by Bloomberg say Rio has already instructed UBS and JPMorgan to structure the deal, and the official "auction process" is expected to be underway in the first half of the year.
Serious bidders include WE Soda, Magris Resources and U.S. Silica Holdings, according to Bloomberg and Reuters, and binding bids are expected to be submitted by June. Given the deposit's long life (reserves into the early 40s) and strategic position in global supply, it is estimated that the package could reach a valuation of up to $2 billion.
Why boron is strategic and who needs it
Boron is one of the lesser known but increasingly important "critical" minerals. It is used in a wide range of industries:
Specialty glasses and ceramics (e.g. heat resistant glass, displays)
Renewable energy - components for wind turbines, solar technology
nuclear energy, insulation and high-resistance materials
fertilisers and agrochemicals
chemical industry, detergents and as an additive for drilling in the oil and gas sector
In 2023/2024, the U.S. Geological Survey and the U.S. Department of the Interior listed boron as a critical mineral due to supply risks, limited substitutes, and high concentration of production outside the U.S. This is what makes Rio Tinto's California project a strategic asset: a large 'domestic' deposit in a country that wants to reduce its reliance on imports for key materials for the energy and high-tech industries.
What the sale could bring to Rio Tinto
For Rio Tinto, the divestment of the pine assets is part of a broader strategy to 'narrow' its portfolio. Last year, CEO Simon Trott unveiled a plan to generate $5-10 billion through a combination of "non-core" asset sales and productivity improvements to allow the company to channel more capital into its core pillars (iron ore, copper, aluminium and new battery metals).
An expected price of up to $2 billion would enable Rio:
strengthen its balance sheet and possibly reduce net debt
free up capital for large growth projects in copper, lithium or iron ore
Simplify the operational structure and management, as the boron operations have a different logic than the company's core mining segments
The market has so far viewed the news positively. Following news of interest from more than a dozen bidders and valuation estimates, Rio Tinto $RIO shares briefly added roughly 1-1.5% in New York, reflecting expectations that the firm can sell the asset at an attractive price in a competitive process.
Impact on the boronmarket and possible scenarios
As Rio Tinto's California complex covers approximately one-third of the world's demand for refined boron, owning these assets will change the market balance. If the assets are taken over by a specialty chemical company or an industrial player such as WE Soda or U.S. Silica, the following may occur:
better vertical integration: linking boron mining with the production of final products (glass, chemicals, fertilisers)
changes in pricing policy and long-term offtake contracts
greater investment in capacity expansion or modernisation of processing if the new owner sees room for margin expansion
Conversely, the entry of a strong private-equity fund could mean a more financially oriented approach - cost optimization, perhaps restructuring of contracts and subsequent sale after a few years with appreciation. But in both cases, the asset is long-lived (reserves into the 40s) and the industry benefits from the long-term trend of electrification, renewables and demand for specialty materials.
For Rio Tinto, it is thus more a question of capital allocation than of exiting a promising segment - the company is betting that it will make $2 billion better in other projects than by continuing to operate a "chemical-oriented" US pine portfolio on its own.