Heavy Minerals
Definition
Minerals with density greater than 2.85 g/cm3, separated from a soil or sediment by a heavy liquid. They typically form 0.1-5% of a sand-grade sample by mass but carry distinctive provenance information inherited from the parent rock.
- Density threshold
- Greater than 2.85 g/cm3
- Separation method
- Heavy liquid
- Typical proportion
- 0.1-5% of a sand-grade sample by mass
- Value
- Provenance information from parent rock
Common questions
Why does such a small fraction of a soil sample carry disproportionate evidential value?+
Even though heavy minerals are a minor part of a sample by mass, their species composition is far more source-specific than the dominant quartz and feldspar, so a small, carefully identified grain population can distinguish soils that look identical otherwise.
What precaution matters when comparing heavy-mineral results between two samples?+
Sample size and grain count must be large enough to be statistically representative, because a very small heavy-mineral fraction means a small sample can easily miss or overrepresent a species by chance, skewing the comparison.
Related terms
- ATi Index
- Apatite to Tourmaline index: [apatite/(apatite + tourmaline)] x 100. Low values indicate advanced weathering or sediment recycling because apatite is dissolved by...
- Bromoform (CHBr3)
- Tribromomethane, density 2.89 g/cm3, historically the standard heavy-separation liquid. Now largely displaced by sodium polytungstate because of its toxicity and regulatory requirements,...
- Provenance
- The documented origin of a media file: the device that captured it, the time and location of capture, the chain of custody...
- Sodium Polytungstate (SPT)
- An aqueous inorganic salt solution used as a non-toxic alternative to bromoform for density separation. Density is tunable by concentration; the 2.85-2.90...
- ZTR Index
- Zircon-Tourmaline-Rutile index: [(zircon + tourmaline + rutile)/total transparent non-opaques] x 100. High values mark texturally and chemically mature sediments that have lost...