Native gold is the only ore of gold, a precious metal. Native gold veins may be good sites for a high-value room, since mining the vein still leaves a valuable gold floor, ready for smoothing and engraving.
Native gold is very common in igneous layers, a bit less in sedimentary layers.
When mined, hunks of native gold are called gold nuggets. Gold nuggets can be smelted to produce 4 gold bars. Gold nuggets can also be smelted with a silver-bearing ore to create the alloy electrum. Using low-value silver ores (such as tetrahedrite) in this reaction will result in a net value increase for your fortress (though the electrum bars are each less valuable than gold bars, you will have twice as many total bars).
Native gold is just as valuable as metallic gold, so if you have a decently skilled stonecrafter and did not start your metal industry yet, native gold mugs are very good to quickly boost the value of your starting fortress and/or buy stuff from an early caravan. However, melting the gold will make far more bars and generally more wealth.
[INORGANIC:NATIVE_GOLD] [ENVIRONMENT:IGNEOUS_ALL:VEIN:100] [ENVIRONMENT:ALLUVIAL:CLUSTER_SMALL:100] [ITEM_SYMBOL:'*'] [METAL_ORE:GOLD:100] [STONE_NAME:gold nuggets] [STATE_NAME:SOLID:native gold] [STATE_NAME:SOLID_POWDER:native gold dust] [STATE_ADJ:ALL_SOLID:native gold] [STATE_NAME_ADJ:LIQUID:molten native gold] [STATE_NAME_ADJ:GAS:boiling native gold] [DISPLAY_COLOR:6:7:1] [TILE:156] [MATERIAL_VALUE:30] [SPEC_HEAT:129] [MELTING_POINT:11915] [BOILING_POINT:15141] [SOLID_DENSITY:19320] [LIQUID_DENSITY:17310] [MOLAR_MASS:196967] [IMPACT_YIELD:175000] [IMPACT_FRACTURE:350000] [IMPACT_STRAIN_AT_YIELD:97] [COMPRESSIVE_YIELD:175000] [COMPRESSIVE_FRACTURE:350000] [COMPRESSIVE_STRAIN_AT_YIELD:97] bulk modulus 180 GPa [TENSILE_YIELD:50000] [TENSILE_FRACTURE:100000] [TENSILE_STRAIN_AT_YIELD:64] young's modulus 78 GPa [TORSION_YIELD:50000] [TORSION_FRACTURE:100000] [TORSION_STRAIN_AT_YIELD:185] [SHEAR_YIELD:50000] [SHEAR_FRACTURE:100000] [SHEAR_STRAIN_AT_YIELD:185] shear modulus 27 GPa [BENDING_YIELD:50000] [BENDING_FRACTURE:100000] [BENDING_STRAIN_AT_YIELD:64] [MAX_EDGE:1000] no swords until you can pick mats [ITEMS_HARD] [IS_STONE]