. . . . "For each COD entry with formula O2 Si in P3121 or P3221 passing the pre-registered ambient filter, the prism-rhombohedron angle 90 + atan(2 c / (sqrt(3) a)) was computed from the refined cell; SD and range across entries compared with the pre-registered thresholds." . . "Measured: 0.3299 standard deviation of the (10-10)^(10-11) interfacial angle across alpha-quartz cells (degrees) (n = 45). Interpretation: Steno observed angles with a goniometer-less eye on natural specimens; here the angle is computed from the refined hexagonal cell (tan of the half-angle from c/a), so the test asks whether independent laboratories find one cell for the species, which is what makes the angles constant. Face lengths are not in the data; the claim's contrast with varying habit is not tested. The classical value is 141 deg 47 min; the mean is reported against it." . "Claim test of steno1669-01: mixed, confidence 0.6" . . . "Planned datasets: cod-search-api" . "claim-test/0.1.0" . "physical" . "Standard deviation above 1 degree: refutes. Between 0.1 and 1 degree, or range above 0.5 degree with SD below 0.1: mixed. Fewer than 10 qualifying entries: inconclusive." . "The COD's celltemp and cellpressure fields are empty for the high-pressure (to 6 GPa) and high-temperature series in this set, so the pre-registered ambient filter admits them; the dispersion the verdict rests on is theirs. The nine entries whose titles name no such conditions have SD 0.03 degree (reported only)." . "The angle is computed from the cell, not measured on a specimen; face lengths are not in the data, so the contrast with varying habit is not tested." . "Over all COD entries with formula O2 Si in space groups P 31 2 1 or P 32 2 1 at ambient conditions (celltemp null or 273-313 K; cellpressure null or <= 0.2 GPa), the standard deviation of the (10-10)^(10-11) interfacial angle is below 0.1 degree and the full range is below 0.5 degree: supports." . "Standard deviation above 1 degree: refutes. Between 0.1 and 1 degree, or range above 0.5 degree with SD below 0.1: mixed. Fewer than 10 qualifying entries: inconclusive." . "0.6"^^ . . "mixed" . "If interfacial angles are constant for a species, the angle between the prism face (10-10) and the rhombohedron face (10-11) of alpha-quartz, which depends only on c/a, is the same in every independently refined alpha-quartz structure." . "For each COD entry with formula O2 Si in P3121 or P3221 passing the pre-registered ambient filter, the prism-rhombohedron angle 90 + atan(2 c / (sqrt(3) a)) was computed from the refined cell; SD and range across entries compared with the pre-registered thresholds." . "Over all COD entries with formula O2 Si in space groups P 31 2 1 or P 32 2 1 at ambient conditions (celltemp null or 273-313 K; cellpressure null or <= 0.2 GPa), the standard deviation of the (10-10)^(10-11) interfacial angle is below 0.1 degree and the full range is below 0.5 degree: supports." . "true"^^ . . "" . "CC0 (COD data are public domain)" . . "Dataset: Crystallography Open Database (COD) search API and CIF files" . . . "sha256:50092d0ab48f382515a0a6d57008c14b2f03aee5912f91fb0486b1a52717a651" . . "delphisci claim tester (claude-fable-5.1; crystals-and-form-tests-1)" . . . "claude-fable-5.1" . . . . . . . . . "2026-11-08T16:24:31.804Z"^^ . . . . . "Claim test of steno1669-01: mixed, confidence 0.6" . . "RSA" . "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAyFHtPB6p0mCjDozxlOY9CmO3nBm7Te3jFbXyLmM+G1tGe47Da0jYIbhkl9Oo1ZjxmCa3LCwlEqK8gj6hEIcL4ahW30JXh9HycfKVk1bugkzMEV15tJdTzAU3sGMFnbNsn43xY2LFLy45tApkRm5byEiM7oRRrooIdwoQKnP4Wzq/bfAoJ9qvW+MGkelyOTd1jbSt+KfmT7xKmDfWzAHddUlWwMX2QJOLxDaffOteTop6ZRgPiNmPJKA/S62Gac9XtSYT3oDkZ6/nr5cxxNLpOyxTf5FPISiCe11xYO/unYjY+mwnOfA8yhJIyx1l0O9I0vpOpn+E5TvyHJV+oSTrvwIDAQAB" . "KE0gEL8FJkcFnjnloGnQZjwTRAtT2qqa4Ga4X1S49eb3dvF7Rvsh1bH0dRZCFm+6AvdyHetzdJqRMAkD61M9DPmL2kANSTVKbK1vgl6dbYEaKTix8GtR2ppA2qoq9QCGujwLfnsOmB7iZA5UfWyDkTlFilMNgHLGGgllxKb6axKBYd2BM0OLCevq70kN4Slgs/vHjc1l8WhoBEoC/hfwIKIHJO9qefU9ibxzs9ZjKdSoWHjZpJzcunyr51DAxLFKZf4bP7YOLG+3ExNGJYfRXyi6PlMdODcz3zyXmSKFTE1Zssr0K+Nh83PqE+7kokHYZQHiPlVWiRrq8bu/7U68Lg==" . . .