can also provide excellent thermal mass, or be used to provide radiant heat. Some stone and brick makes an ideal flooring or exterior paving material, cool in summer and possessing good thermal properties for passive solar heating. Caliche block has been produced for applications similar to stone and brick mentioned above. Caliche or earth material block has special structural and finishing characteristics. Rammed earth is more often considered for use in walls, although it can also be used for floors. Rammed earth and caliche block can be used for structural walls, and offer great potential as low-cost material alternatives with low embodied energy. In addition, such materials are fireproof. Caliche block and rammed earth can be produced on-site. It is very important to have soils tested for construction material use. Some soils, such as highly expansive or bentonite soils, are not suitable for structural use. Testing labs are available in most areas to determine material suitability for structural use and meeting codes. Soils for traditional adobe construction are not found in some areas, but other soils for earth building options are available. Many areas have a high percentage of soils suitable for ramming. (Official areas are approximately 19,610 acres in the Austin, TX area, according to the US. Department of Agriculture). Caliche is also abundant in many areas (covering 14% of the Austin geographic area, for instance) and is readily available locally. See also Structure of Earth References External links BGS Open Data Earth Materials Ontologies Economic geology