Sigma Lithium rebound and Grota do Cirilo update: key project notes for mine planners
Reviewed by Joe Ashwell

First reported on MINING.com
30 Second Briefing
Sigma Lithium’s share price jumped up to 17% to about $14.50 in New York, after the company announced an additional sale of 100,000 tonnes of high-purity lithium fines at current market prices and rejected Brazilian media reports of an “operational injunction” at Grota do Cirilo as fake, short-seller-driven claims. Management said remobilisation at the Minas Gerais site is on track to finish this month, with the existing plant rated at 270,000 tonnes per year of lithium oxide concentrate (about 38,000–40,000 tonnes LCE). A second plant under construction is planned to double that capacity.
Technical Brief
- Grota do Cirilo in Minas Gerais is described as one of the largest, highest‑grade hard‑rock lithium deposits globally.
- Brazilian media reports alleged shutdown of waste piles due to environmental and safety risks at the operation.
- Sigma states the shutdown claims relied on falsified government websites posing as official regulatory sources.
- Management characterises the allegations as part of a “defamatory campaign” designed to benefit short sellers.
- The company has not yet provided further technical or regulatory detail in response to MINING.COM’s request for comment.
Our Take
Sigma Lithium’s roughly $1.6 billion market capitalisation keeps it well below the majors tracked in MINING.COM’s Top 50 ranking, but the Grota do Cirilo operation in Minas Gerais still sits in the core ‘critical-mineral’ cluster that investors are watching alongside copper and rare earths in our recent coverage.
With Grota do Cirilo in Brazil supplying lithium oxide concentrate into North American supply chains that touch Texas and Tennessee, Sigma Lithium is positioned to benefit from US policy support for critical minerals without being a US-domiciled producer, a pattern seen across several Latin American lithium names in our database.
The 17% share price move this month underscores how sensitive listed lithium producers are to operational or environmental headlines; in our coverage of 77 lithium-tagged pieces, comparable single-day swings are typically associated with either permitting scares or new offtake/expansion signals rather than routine quarterly updates.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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