Heavy-Mineral Suite
Definition
The assemblage of high-specific-gravity minerals (greater than about 2.85 g/cm3) present in a sediment sample, typically including zircon, tourmaline, garnet, and hornblende. The proportions reflect the bedrock that eroded to form the sediment, making the suite a geographic fingerprint.
- Composition
- Zircon, tourmaline, garnet, hornblende, others
- Density threshold
- About 2.85 g/cm3
- Reflects
- Bedrock of the erosion source
- Forensic role
- Geographic fingerprint
Common questions
Why is the heavy-mineral suite more useful for provenance than bulk soil colour or texture?+
Colour and texture change with weathering, organic content and moisture, but the heavy-mineral assemblage is inherited from the source rock and survives transport and burial largely intact, giving a more stable geographic signal than surface properties.
How do examiners compare a heavy-mineral suite between a suspect item and a scene?+
They typically count and identify a statistically adequate number of grains under a polarising microscope, express the result as relative percentages of each mineral species, and compare that proportional profile rather than looking for one exact match.
Related terms
- Comparative Mineralogy
- The systematic comparison of mineral assemblages from a questioned sample and a reference sample to assess whether they share the same geographic...
- Forensic Geology
- The application of geological sciences to legal and investigative problems, treating earth materials such as soil, rock, mineral, sediment, and dust as...
- Geo-Provenance
- The determination of geographic origin of a geological material based on its physical, mineralogical, or geochemical characteristics. The same concept that geologists...
- Polarised Light Microscopy (PLM)
- A microscopy technique in which polarised light is passed through a thin section or grain mount, revealing optical properties (birefringence, extinction angle,...
- Trace Evidence
- Small quantities of material transferred between people, objects, and locations during contact. Forensic geology focuses on the geological subset of trace evidence:...