The Tirunelveli district in Tamil Nadu, India has many geological features, including hard rock formations, crystalline limestone, and minerals. 

• Charnockite: An acidic to intermediate type of hard rock that covers almost 99% of the district 
   
• Granite gneisses, amphibolites, and granulites: Rock types found in the Sivanmalai Syenite Complex 
   

• Crystalline limestone: A notable economic mineral found in the district
• Multi-color dimension stone: A notable economic mineral found in the district
• Garnet and ilmenite sand: Notable economic minerals found in the district
• Graphite, mica, and gemstones: Minor occurrences of these minerals have been reported in the district