The occurrence of hydrothermally altered volcanic rock in eastern Flores is geologically plausible and is consistent with the regional volcanic and geothermal setting.
Pain Haka is located at the northeastern extremity of Flores in an area described archaeologically as an uplifted volcanic terrain bordered by raised coral terraces. The archaeological site itself occupies a coastal sedimentary setting, but the broader landscape is volcanic in origin.
Independent geothermal investigations in East Flores document active and fossil hydrothermal systems associated with volcanic complexes. The Ile Ange geothermal prospect extends across Ile Mandiri, Tanjung Bunga, and Larantuka. The area contains volcanic landforms, fault- and fracture-controlled permeability, hot springs, fumaroles, and other geothermal manifestations. Geological investigations of the related Ile Angin–Ile Padung and Oka geothermal areas also document altered volcanic rocks and hydrothermal alteration of andesitic lava along fracture systems.
These data establish that hydrothermal alteration of volcanic rocks is an appropriate geological process for eastern Flores.
Chlorite is not, by itself, a rare or anomalous mineral.
Chlorite-group minerals occur in a wide range of metamorphic, diagenetic, geothermal, and hydrothermal environments. In volcanic geothermal systems, chlorite is particularly characteristic of transitional argillic–propylitic and propylitic alteration assemblages. A commonly cited propylitic assemblage includes chlorite, albite, carbonate, and epidote. Hydrothermal chlorite may form through mineral replacement or precipitation associated with the circulation of heated fluids through volcanic host rocks and fracture systems.
Accordingly, the analytical significance of chlorite in an archaeological ceramic does not derive from the mineral name alone.
A determination of chlorite-bearing hydrothermally altered volcanic rock carries more geological information than the identification of an isolated chlorite grain. It indicates a lithic fragment derived from a rock that had already undergone a sequence of geological processes before incorporation into the ceramic fabric:
primary volcanic rock formation
→ circulation of hydrothermal fluids
→ secondary mineral alteration, including chlorite formation
→ fragmentation of the altered host rock
→ incorporation of the lithic fragment into the ceramic body
The inclusion therefore represents a fragment of a pre-existing geological material with a potentially identifiable source environment.
Ceramic petrography routinely distinguishes clay matrix, mineral grains, rock fragments, and inorganic or organic temper within archaeological ceramic fabrics.
The mineralogical and textural composition of these components can be used to investigate raw-material selection, ceramic production technology, geological provenance, and the movement of pottery or ceramic raw materials. Petrographic analysis is therefore directly relevant when a ceramic contains a distinctive lithic component whose geological occurrence may be spatially restricted.
The identification of a hydrothermally altered volcanic lithic inclusion therefore raises a source problem rather than merely a mineral-identification problem.
The relevant comparison is not limited to the presence or absence of chlorite. Source assessment would require consideration of the complete lithological and petrographic character of the inclusion, including associated mineral phases, texture, alteration style, chemistry, and its relationship to candidate geological sources.
Petrographic provenance studies demonstrate that rock or sand temper can preserve information about the bedrock or sedimentary environment from which the material was obtained. Such information may be used to discriminate between local manufacture, acquisition of raw materials from another locality, and movement of finished vessels.
The presence of a distinctive lithic fragment within a ceramic body does not, by itself, establish deliberate addition.
At least three interpretations must remain open during preliminary analysis.
Natural inclusion
The altered-rock fragment may have been naturally present in clay, sand, or other sediment collected for ceramic production. In this case, its presence reflects the geology of the raw-material source without requiring deliberate selection of the altered rock.
Deliberately added temper
Altered volcanic rock may have been collected separately, crushed, and intentionally incorporated into the clay body. Confirmation of such a practice would require textural and comparative evidence beyond simple mineral identification.
Non-local ceramic or raw material
The geological material represented by the inclusion may not occur within the immediate archaeological locality. The vessel, the clay, or the temper component may therefore have been transported from another source area.
Distinguishing these possibilities normally requires analysis of inclusion size, morphology, angularity, sorting, abundance, spatial distribution within the ceramic matrix, and comparison with local clay, sediment, rock, and ceramic reference samples. Natural lithic inclusions and intentionally introduced temper can overlap in appearance, and classification therefore requires contextual as well as petrographic evidence.
The analytical sequence may therefore be defined as follows:
chlorite-group phase
→ chlorite-bearing altered lithic inclusion
→ hydrothermally altered volcanic source rock
→ candidate source geology
→ raw-material provenance
The principal significance of the preliminary mineralogical result is thus not that chlorite has been detected.
The significant result is that a component of the ceramic fabric can potentially be associated with a specific type of geological environment.
For an archaeological assemblage in eastern Flores, the presence of such material is regionally plausible because volcanic and hydrothermal systems are documented in the wider area. Regional plausibility, however, is not equivalent to local provenance. A hydrothermally altered volcanic lithic inclusion cannot be assigned to TB-3, Pain Haka, or any other locality solely on the basis of chlorite identification.
The required analytical question is therefore one of geological source attribution:
What geological source could have supplied the chlorite-bearing hydrothermally altered volcanic lithic material incorporated into this ceramic fabric?
Until candidate raw-material sources are identified and compared, the inclusion must remain consistent with multiple explanations: natural incorporation from a local sediment source, deliberate addition of crushed altered rock, or introduction of ceramic material or raw materials from outside the immediate archaeological locality.