Add MindatLoader for Mindat.org mineralogical database access

Adds a new loader class for querying and caching mineral data from the
Mindat API via the openmindat Python package. Features include:
- Fetch minerals by element, name, or ID
- Query IMA-approved minerals
- Fetch locality data for minerals
- Support for all DOE critical mineral elements
- Predefined element groups (REE, PGM, battery metals, etc.)
- Local caching of API results for offline access

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: nmwashton

src/cmm_data/__init__.py

@@ -35,6 +35,9 @@ def __getattr__(name):
     elif name == "OECDSupplyChainLoader":
         from .loaders.oecd_supply import OECDSupplyChainLoader
         return OECDSupplyChainLoader
+    elif name == "MindatLoader":
+        from .loaders.mindat import MindatLoader
+        return MindatLoader
     raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
 
 
@@ -126,6 +129,7 @@ def iter_corpus_documents(**kwargs):
     "GAChronostratigraphicLoader",
     "NETLREECoalLoader",
     "OECDSupplyChainLoader",
+    "MindatLoader",
     # Convenience functions
     "load_usgs_commodity",
     "load_ore_deposits",

src/cmm_data/config.py

@@ -64,6 +64,7 @@ class CMMDataConfig:
     ga_chronostrat_dir: str = "GA_149923_Chronostratigraphic"
     netl_ree_dir: str = "NETL_REE_Coal"
     oecd_supply_dir: str = "OECD_Supply_Chain_Data"
+    mindat_dir: str = "Mindat"
 
     # Caching settings
     cache_enabled: bool = True
@@ -98,6 +99,7 @@ def get_path(self, dataset: str) -> Path:
             "netl": self.netl_ree_dir,
             "netl_ree": self.netl_ree_dir,
             "oecd": self.oecd_supply_dir,
+            "mindat": self.mindat_dir,
         }
 
         rel_path = path_map.get(dataset.lower())
@@ -115,7 +117,7 @@ def validate(self) -> dict:
         """
         datasets = [
             "usgs_commodity", "usgs_ore", "osti", "preprocessed",
-            "ga_chronostrat", "netl_ree", "oecd"
+            "ga_chronostrat", "netl_ree", "oecd", "mindat"
         ]
 
         status = {}

src/cmm_data/loaders/__init__.py

@@ -1,5 +1,11 @@
 """Data loaders for CMM datasets."""
 
 from .base import BaseLoader
+from .mindat import MindatLoader, CRITICAL_ELEMENTS, ELEMENT_GROUPS
 
-__all__ = ["BaseLoader"]
+__all__ = [
+    "BaseLoader",
+    "MindatLoader",
+    "CRITICAL_ELEMENTS",
+    "ELEMENT_GROUPS",
+]