In 2013 Australian startup, Calix Limited, built and commissioned a commercial-scale demonstrator plant at Bacchus Marsh, Victoria, based on their patented technology, to showcase a transformational calcination process for creating reactive oxide products whilst also capturing carbon dioxide (CO2) released during the reaction. Integral to the successful commercial introduction of the technology was the quality of reactive magnesium oxide (magnesia, MgO) product achieved using cryptocrystalline magnesite (MgCO3) from the Myrtle Springs mine in South Australia. Calix has successfully marketed the product, as a magnesium hydroxide (Mg(OH)2) slurry, for pH and odour control in sewer and wastewater industries and as an effective coating for protection of sewer concrete infrastructure against acid corrosion. New applications in aquaculture and agriculture are currently under evaluation, with field trials in Australia and overseas. Research projects are underway also into products for the health and pharmaceutical sectors, 3D printing, advanced building materials and catalysts. Magnesia with a very high surface area underpins much of this activity. The relative contributions from characteristics specific to the raw magnesite feedstock and those from refinements to the kiln operating conditions to create the highly reactive MgO product are the subject of ongoing investigation. In this regard, the occurrence and properties of marine sedimentary magnesite from the northern Flinders Ranges are somewhat unique amongst global magnesite deposits. Of equal or greater significance for the Calix kiln technology is the effective capture of pure CO2 released during calcination. This aspect has attracted international interest, with European cement and lime producers partnering with Calix in the design and build of a demonstration plant at HeidelbergCement’s Lixhe cement plant in Belgium. Total emissions from cement manufacture constitute ~8% of global anthropogenic CO2 emissions. Over the next two years, the Calix kiln technology will be fully tested and evaluated as a key component of the LEILAC (Low Emissions Intensity Lime and Cement) project to largely eliminate CO2 process emissions from cement and lime manufacture as an important contribution towards the EU target of cutting CO2 emissions to 80% below 1990 levels by 2050. The significance of the new technology for further development of South Australian magnesite resources is considered here in the context of: global magnesite markets and sources; geology and characteristics of sedimentary magnesite deposits of the northern Flinders and Willouran ranges; previous work to evaluate and develop the sedimentary magnesite resources; history of development of the Calix kiln technology; new market opportunities for cryptocrystalline magnesite. Growth in markets where high-activity MgO provides advantage, and where low levels of CaO and talc impurities are tolerated, appear set to underpin further development of South Australia’s unique sedimentary magnesite resources.