{"nrhp_refnum":"80000653","name":"Massachuetts Hornfels-Braintree Slate Quarry","other_names":[],"category":"site","location":{"address":null,"address_restricted":true,"city":"Milton","county":"Norfolk County","state":"MA","lat":null,"lon":null,"geom_source":null},"listed_date":"1980-09-25","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Industry","Prehistoric"],"significance_levels":["state"],"summary":null,"photo":{"url_800":"https://nationalhistoricalregister.com/media/80000653/1bb88dff9a-800.webp","url_1600":"https://nationalhistoricalregister.com/media/80000653/1bb88dff9a-1600.webp","licence":"Public domain","author":"Title by User:Jsmeslwoodward","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Hornfels_Map.png\" rel=\"noopener\">Title by User:Jsmeslwoodward</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Hornfels_Map.png"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":null,"wikipedia":"https://en.wikipedia.org/wiki/Massachusetts_Hornfels-Braintree_Slate_Quarry","wikidata":"https://www.wikidata.org/wiki/Q6784290"},"indexable":false,"url":"https://nationalhistoricalregister.com/massachusetts/norfolk-county/massachuetts-hornfels-braintree-slate-quarry-80000653/"}