ATi index
Definition
Apatite to Tourmaline index: [apatite/(apatite + tourmaline)] x 100. Low values indicate advanced weathering or sediment recycling because apatite is dissolved by weak acids while tourmaline is stable.
Related terms
- 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,...
- Heavy minerals
- 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...
- Provenance
- In ceramic petrology, the geographic area from which the raw materials (clay and temper) were sourced; distinct from production place (where the...
- 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...
Explained in
- Density-Gradient Separation and Heavy-Mineral AnalysisApatite to Tourmaline index: [apatite/(apatite + tourmaline)] x 100. Low values indicate advanced weathering or sediment recycling because apatite is dissolved...