{
  "coal_region_system": {
    "resource_type": "coal",
    "description": "Coal feature selection based on region mass and biome compatibility",

    "features": {
      "rich_coal_seam": {
        "display_name": "Rich Coal Seam",
        "incompatible_biomes": ["hot_desert", "cold_desert", "alpine", "wetlands"],
        "frequent_biomes": ["temperate_forest", "hills"],
        "minimum_region_mass": 100,
        "quality_base": "premium",
        "extraction_difficulty": "medium",
        "budget_impact": 4,
        "description": "High-quality coal requiring substantial geological compression"
      },

      "coal_seam": {
        "display_name": "Coal Seam",
        "incompatible_biomes": ["hot_desert", "cold_desert", "alpine"],
        "frequent_biomes": ["temperate_forest", "grassland", "hills"],
        "minimum_region_mass": 50,
        "quality_base": "standard",
        "extraction_difficulty": "medium",
        "budget_impact": 3,
        "description": "Standard coal in medium-strength regions"
      },

      "coal_outcrop": {
        "display_name": "Coal Outcrop",
        "incompatible_biomes": ["hot_desert", "alpine", "tropical_rainforest"],
        "frequent_biomes": ["temperate_forest", "grassland", "hills", "scrubland"],
        "minimum_region_mass": 25,
        "quality_base": "standard",
        "extraction_difficulty": "easy",
        "budget_impact": 2,
        "description": "Surface coal accessible in small regions"
      },

      "surface_coal": {
        "display_name": "Surface Coal",
        "incompatible_biomes": ["hot_desert", "cold_desert", "alpine", "wetlands"],
        "frequent_biomes": ["temperate_forest", "grassland", "scrubland"],
        "minimum_region_mass": 15,
        "quality_base": "low",
        "extraction_difficulty": "very_easy",
        "budget_impact": 1,
        "description": "Weathered coal in small regions"
      },

      "lignite_deposit": {
        "display_name": "Lignite Deposit",
        "incompatible_biomes": ["hot_desert", "cold_desert", "alpine", "rocky_plateau"],
        "frequent_biomes": ["temperate_forest", "grassland"],
        "minimum_region_mass": 75,
        "quality_base": "medium",
        "extraction_difficulty": "medium",
        "budget_impact": 2,
        "description": "Brown coal in medium sedimentary regions"
      },

      "peat_bog": {
        "display_name": "Peat Bog",
        "incompatible_biomes": ["hot_desert", "cold_desert", "alpine", "rocky_plateau"],
        "frequent_biomes": ["wetlands"],
        "minimum_region_mass": 10,
        "quality_base": "low",
        "extraction_difficulty": "easy",
        "budget_impact": 1,
        "description": "Early coal formation in wetland environments"
      }
    },

    "selection_logic": {
      "step_1": "Check region mass against minimum_region_mass",
      "step_2": "Filter out features with incompatible biomes",
      "step_3": "Prioritize features with frequent biomes for this location",
      "step_4": "Select from available features",
      "fallback": "If no features available, place generic coal"
    },

    "mass_categories": {
      "tiny_region": {"mass_range": [10, 25], "typical_features": ["peat_bog", "surface_coal"]},
      "small_region": {"mass_range": [25, 50], "typical_features": ["coal_outcrop", "surface_coal"]},
      "medium_region": {"mass_range": [50, 100], "typical_features": ["coal_seam", "lignite_deposit"]},
      "large_region": {"mass_range": [100, 300], "typical_features": ["rich_coal_seam", "coal_seam"]},
      "huge_region": {"mass_range": [300, 1000], "typical_features": ["rich_coal_seam"]}
    }
  }
}