Quarrying generates significant changes in the grasslands, by reducing ecological functions, reducing connectivity, impairing biodiversity, and degrading soil. Unlike other forms of destruction such as agriculture or urbanization, mining is characterized by eliminating soil and exposing the bedrock, facilitating groundwater contamination processes. Quarrying in Pampean grassland has been expanding for a century and little is known about the extent and distribution of quarries over the native environment. In this work, we analyze the spatiotemporal variation of quarrying activity on the Highland grassland in the Tandilia mountains of Argentina. Based on Landsat 5, 7, and 8 satellite imagery, from 1996 to 2022, and using QGIS software, we identified the location and extension of quarries, and we analyzed their change through time. Quarries covered 6428 ha, which was originally part of the Pampean grassland. The number of open quarries increased by 129%, from 69 in 1996 to 158 in 2022, and the area used for this activity increased by 172%, with a greater expansion being detected in the last ten years. At least 87 quarries were abandoned in 2022. Quarries are often abandoned without any kind of remediation, leading to further ecosystem deterioration. The current extension of quarrying activity (active and abandoned quarries) reduced the connectivity and a significant area (5.2%) of the Highland grassland of the Tandilia Mountains. Grassland conservation planning should include quarrying as a significant threat, and management actions must be considered to reduce its impact.