iSamples Query Substrate — Snapshot 202609

Parquet files that together constitute the cross-source query substrate for iSamples material-sample records as of the 202609 release (6,026,242 located samples, 20,822,565 wide-format records across 4 sources: SESAR, OpenContext, GEOME, Smithsonian). These files back the browser-based Interactive Explorer at isamples.org and the Python reference notebooks at github.com/isamplesorg/examples. MANIFEST.json holds per-file SHA-256 checksums; README.md has file roles, provenance and usage notes. Derived from the iSamples aggregated Zenodo export (doi:10.5281/zenodo.15278211, April 2025). This is a later version of the January 2026 snapshot (doi:10.5281/zenodo.21288719), which remains available and includes the narrow/graph file.