{"L1_core": {"domain": "material", "category": "metal", "subcategory": "non-ferrous", "atomic_number": 29, "element_symbol": "Cu"}, "L5_metadata": {"updated": "2026-01-04", "version": "1.0"}, "L3_standards": {"en": ["EN 1652"], "iso": ["ISO 1337"], "astm": ["ASTM B152"]}, "L2_properties": {"physical": {"density_g_cm3": 8.96, "melting_point_c": 1085, "thermal_conductivity_w_mk": 401, "electrical_conductivity_ms_m": 59.6}, "mechanical": {"elastic_modulus_gpa": 130, "tensile_strength_mpa": [210, 370]}, "characteristics": ["excellent-conductor", "antimicrobial", "malleable", "recyclable"]}, "L4_applications": ["electrical-wiring", "plumbing", "electronics", "heat-exchangers"]}