But Still the question remains: "How to find if a coulmn is part of a Functional Index?" The following query errors with "ORA-00932: inconsistent datatypes: expected - got LONG"...

SELECT i.index_name,
       i.table_name,
       e.column_expression
FROM   user_indexes i
JOIN   user_ind_expressions e
ON     i.index_name = e.index_name
WHERE  to_lob(e.column_expression) LIKE '%<COLUMN_NAME%';

Any help in this matter is appreciated