When sourcing basalt wool (also known as rock wool), the most critical factor is density, which typically ranges from 40kg/m³ to 200kg/m³ depending on the application. For thermal insulation in buildings, a density of 60-100kg/m³ is standard, while industrial furnace insulation requires higher densities. You must also verify the Thermal Conductivity (Lambda Value), which should ideally be between 0.033 and 0.040 W/(m·K) at room temperature. Additionally, ensure the material has a melting point above 1000°C to guarantee true fire resistance.