{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.sunstone","code":"thing-q1895983","url":"https://ver.cy/models/thing/q1895983/","name":"sunstone","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.3","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.BLT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"A crystal, according to Icelandic sagas and later hypotheses, used by Norse navigators to locate the sun in overcast or twilight conditions by observing polarised skylight, proposed to have been Iceland spar or calcite, cordierite or tourmaline, and tested experimentally by modern researchers with mixed results; the sunstone remains unproven as a historical navigational aid, though a calcite crystal was found in a 16th-century English shipwreck, and the term also names a feldspar gem.","purpose":"Let an agent explain the sunstone hypothesis and its evidence, relay saga references, candidate minerals and experiments from historical and scientific sources with attribution, describe the state of the debate, and distinguish the navigational sunstone from the feldspar gemstone.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Polarised skylight","Saga origin","Unproven historically","Modern experiments"],"structure":{"bundles":[{"id":"understand","name":"Understand","description":"What the sunstone is.","layers":[{"id":"definition","name":"Definition","description":"Definition and hypothesis.","findings":[{"id":"definition-finding","name":"Definition","description":"Definition.","questions":[{"text":"What is the sunstone hypothesis, and how might a crystal locate the sun through polarised light?","kind":"definition"},{"text":"Is the question about the navigational hypothesis or the feldspar gem?","kind":"boundary"}]}]},{"id":"candidates","name":"Candidates","description":"Candidate minerals.","findings":[{"id":"candidates-finding","name":"Candidates","description":"Candidates.","questions":[{"text":"Why are Iceland spar, cordierite and tourmaline proposed, and how would each work?","kind":"definition"},{"text":"Which entry fits the specific mineral?","kind":"action"}]}]}]},{"id":"evidence","name":"Evidence","description":"Evidence.","layers":[{"id":"sagas","name":"Sagas","description":"Saga sources.","findings":[{"id":"sagas-finding","name":"Sagas","description":"Sagas.","questions":[{"text":"What do the sagas say about the solarsteinn, and how do scholars interpret the passages, with positions attributed?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]},{"id":"experiments","name":"Experiments","description":"Experiments and finds.","findings":[{"id":"experiments-finding","name":"Experiments","description":"Experiments.","questions":[{"text":"What have experiments and the Alderney wreck crystal shown, with findings attributed?","kind":"provenance"},{"text":"Is the presentation attributed and cautious?","kind":"boundary"}]}]}]},{"id":"debate","name":"Debate","description":"Debate.","layers":[{"id":"status","name":"Status","description":"Status of the hypothesis.","findings":[{"id":"status-finding","name":"Status","description":"Status.","questions":[{"text":"How do historians and scientists assess the sunstone hypothesis today, with positions attributed?","kind":"provenance"},{"text":"Which sources are cited?","kind":"provenance"}]}]},{"id":"navigation","name":"Navigation","description":"Norse navigation.","findings":[{"id":"navigation-finding","name":"Navigation","description":"Navigation.","questions":[{"text":"What other methods did Norse navigators use, and where is the sunstone in that picture?","kind":"provenance"},{"text":"Which entry fits Viking navigation?","kind":"action"}]}]}]},{"id":"context","name":"Context","description":"Culture.","layers":[{"id":"culture","name":"Culture","description":"Popular culture.","findings":[{"id":"culture-finding","name":"Culture","description":"Culture.","questions":[{"text":"How has the sunstone featured in documentaries, fiction and games?","kind":"provenance"},{"text":"Which entry fits Vikings in popular culture?","kind":"action"}]}]},{"id":"gem","name":"Gem","description":"The gemstone.","findings":[{"id":"gem-finding","name":"Gem","description":"Gem.","questions":[{"text":"What is the feldspar sunstone, and where is it covered?","kind":"provenance"},{"text":"Which entry fits sunstone (gem)?","kind":"action"}]}]}]}]},"agentConduct":{"may":["Explain the sunstone hypothesis, the saga sources and the experiments that tested it.","Distinguish the navigational sunstone from the gemstone of the same name."],"mustNot":["Present the sunstone hypothesis as proven.","Overinterpret saga passages as technical records.","Confuse the navigational sunstone with the gemstone.","Advise anyone to navigate at sea by a sunstone in place of proper instruments."],"requiresHuman":["Publishing new claims about archaeological finds linked to the hypothesis."]},"ethics":{"considerations":["Popular stories about Viking technology can outrun the evidence.","Sagas are cultural heritage and should be read with care."],"affectedParties":["Readers and learners","Nordic heritage communities"]},"owners":{"steward":"Nobody: a historical hypothesis held in common.","roles":[],"masterSystems":[]},"relations":[{"target":"Q3565782","type":"parent","note":"registry parent class"},{"target":"navigational aid","type":"related","note":"in registry terms, hypothetically"},{"target":"Iceland spar","type":"related","note":"among other minerals"},{"target":"polarization","type":"related","note":"of skylight"},{"target":"sunstone (gem)","type":"related","note":"a feldspar"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.sunstone","Wikidata: Q1895983 (https://www.wikidata.org/wiki/Q1895983)"]},"properties":{"applicability":"required","items":["saga references: Rauoulfs thattr and others note - 13th-14th century texts","Alderney wreck crystal: calcite mineral - ship lost 1592","polarisation principle: Rayleigh scattering note"]},"recognition":{"applicability":"required","items":["Hypothesised Norse navigation crystal","Iceland spar, cordierite and tourmaline as candidates","The gem sunstone is a feldspar; the compass is a magnetic instrument","A transparent crystal, possibly a rhomb of Iceland spar."]},"capabilities":{"applicability":"required","items":["explain the hypothesis","relay evidence and experiments","describe the debate","distinguish from the gemstone"]},"hazards":{"applicability":"required","items":["Presenting the hypothesis as proven","Confusing with the gemstone","Overinterpreting saga passages"]},"interfaces":{"applicability":"required","items":["No regulation; heritage protection of relevant wreck finds"]},"context":{"applicability":"required","items":["Hypothetically, locating the sun for navigation.","Iceland spar or calcite hypothesis","cordierite hypothesis","tourmaline hypothesis","experimental reconstructions","the feldspar gem sunstone as a homonym"]}},"sources":[{"title":"Wikidata item Q1895983: sunstone","url":"https://www.wikidata.org/wiki/Q1895983","note":"identity and sense of the item"},{"title":"Wikipedia: Sunstone (medieval)","url":"https://en.wikipedia.org/wiki/Sunstone_%28medieval%29","note":"general description of the item"}],"openQuestions":["Should Iceland spar and Viking navigation be separate primary entries?","How should historical and scientific sources be linked?","How should the evidential status be recorded?"],"resources":{"spec":"/models/things/publications/thing-q1895983/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q1895983/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-13T06:52:40Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-06T19:51:56+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}