heavy minerals and its uses as indicator of provenance

what are the heavy minerals? 

Heavy minerals: are those which have specific gravity greater than quartz and feldspar. the specific gravity of quartz is about 2.65 and for feldspar t varies in between 2.50 to 2.78.

(specific gravity can be calculated by taking the ratio of absolute density of the mineral and absolute density of water at 4*C.)

• heavy minerals also defined for practical purposes as all those minerals having specific gravity greater than that of Bromoform, which have specific gravity 2.87 at 20*C.
• bromoform is a brominated organic solvent.

stability of heavy minerals; 

least stable : barite, augite, apatite, olivine etc.

most stable : zircon, tourmaline, rutile, garnet. 

Heavy minerals are useful in determination of provenance.

before going into the details of how heavy minerals are used to determine the nature of provenance, lets get a brief idea of provenance.

provenance: the literal meaning of the this word is "to origin from ", that is the source area or the source of the sediments is called the Provenance. the nature of the sediments is primarily depends upon the nature of the source rock and the climatic and the environmental conditions prevailing there. so in nutshell PROVENANCE  can be defined as the source area, or source of the sediments and the climatic, environmental conditions prevailing at the source.

Terrigeneous or Clastic sediments which have derived outside the basin or derived from the land part bear the imprints of source rocks. so in order to decipher the provenance, we need to focus on the clastic or terrigeneous sediments. 

To decipher the provenance several minerals have been utilised such as quartz, feldpars, heavy minerals. among these, heavy minerals are the most important because specific set of heavy minerals found in a particular type of rocks as in igneous, metamorphic and sedimentary rocks itself. 

heavy minerals as provenance indicator :    

              mineral assemblage                                                                        source rock

1.   zircon, barite, garnet, rutile, iron ores                                          reworked sediments 
2.  apatite, andalusite, kyanite, sillimanite, zoisite, garnet                 metamorphic rocks
3. chromite, magnetite, hypersthene, augite, diopside, olivine          basic igneous rocks
4.  flourite, topaz, garnet, monazite                                                     granites and pegmatites
5. biotite, muscovite, tourmaline, rutile, hornblende                           acidic igneous rocks.                             

ask your doubts for better understanding.