section_path: Physical properties/Other properties
section_name: Other properties
paragraph_text: Other properties
  
  Other properties can be used to diagnose minerals. These are less general, and apply to specific minerals.
  
  Dropping dilute acid (often 10% HCl) onto a mineral aids in distinguishing carbonates from other mineral classes. The acid reacts with the carbonate () group, which causes the affected area to effervesce, giving off carbon dioxide gas. This test can be further expanded to test the mineral in its original crystal form or powdered form. An example of this test is done when distinguishing calcite from dolomite, especially within the rocks (limestone and dolomite respectively). Calcite immediately effervesces in acid, whereas acid must be applied to powdered dolomite (often to a scratched surface in a rock), for it to effervesce. Zeolite minerals will not effervesce in acid; instead, they become frosted after 5–10 minutes, and if left in acid for a day, they dissolve or become a silica gel.
  
  Magnetism is a very conspicuous property of a few minerals. Among common minerals, magnetite exhibits this property strongly, and magnetism is also present, albeit not as strongly, in pyrrhotite and ilmenite. Some minerals exhibit electrical properties – for example, quartz is piezoelectric – but electrical properties are rarely used as diagnostic criteria for minerals because of incomplete data and natural variation.
  
  Minerals can also be tested for taste or smell. Halite, NaCl, is table salt; its potassium-bearing counterpart, sylvite, has a pronounced bitter taste. Sulfides have a characteristic smell, especially as samples are fractured, reacting, or powdered.
  
  Radioactivity is a rare property found in minerals containing radioactive elements. The radioactive elements could be a defining constituent, such as uranium in uraninite, autunite, and carnotite, or present as trace impurities, as in zircon. The decay of a radioactive element damages the mineral crystal structure rendering it locally amorphous (metamict state); the optical result, termed a radioactive halo or pleochroic halo, is observable with various techniques, such as thin-section petrography.