Microscopes
Stereo-zoom microscope
“Suzy” is our SZ61 stereo-zoom microscope and is capable of magnifications of up to x180. This microscope has an external oblique light source, allowing specimens to be viewed in three-dimensions.
Compound-light microscope
“Baxter” is our BX61 compound vertical incident-light microscope (aka a metallographic microscope) with objective lenses allowing specimens to be viewed under magnifications of x100, x200, x500 and x1000. This microscope has an internal light source that permits both reflected and transmitted light for documenting both usewear in situ on the artefact surface and residues that have been extracted and prepared on glass slides.
Solvent Extractions and Residue Analysis
Solvent extractions
MicroTrace Archaeology utilises a number of sampling strategies to recover residues adhering to the surfaces of stone and other artefacts. These most often include pipette extractions using a variety of solvents, and ultrasonication of the artefact edge. Extracted materials are then prepared on glass slides and examined under transmitted light using our Olympus BX61 compound light microscope.
Residue sampling can be done on site and is a convenient way to examine residue traces on items that cannot be transported to the lab. Such items may include museum specimens, bulky items such as large grinding stones and bedrock grinding patches.
Biological staining of extracted residues
MicroTrace Archaeology uses a number of biological stains to confirm the presence of animal and plant derived residues in solvent extractions. These include:
- Orange G for the staining of collagen and keratin – used to confirm the presence of animal derived proteins.
- Methylene Blue for the staining of plant tissue, including plant cell walls and cellulose.
- Congo Red for the staining of damaged and gelatinised starch grains.
These stains have been approved by the BIOLOGICAL STAIN COMMISSION, Inc. and are routinely used in microscopic examination of extracted residues.
Usewear Impressions
When usewear cannot be documented directly from the artefact, negative impressions can be taken from the artefact surface that can later be examined under high magnification using our Olympus BX61 compound light microscope. MicroTrace Archaeology uses high resolution impression material so that even the most minute wear features can be observed under the microscope at magnifications up to at least 500×, which is suitable for study of polish, microtopographic leveling, striations and grain rounding.
These impressions provide an opportunity to examine usewear features on bedrock grinding/pounding patches and bulky items such as grinding stones that cannot easily be transported to the lab.