Oracle - Index Information (https://app.pluralsight.com/library/courses/oracle-performance-tuning-developers/table-of-contents)

index_info.sql

select ix.owner, ix.index_name, ix.table_name,
    ix.distinct_keys, ix.leaf_blocks,
    s.blocks as segment_blocks,
    s.bytes / 1048576 as size_in_mb,
    to_char(ix.last_analyzed, 'YYYY-MM-DD HH24:MI') as last_analyzed
from all_indexes ix, dba_segments s
where ix.owner = s.owner and ix.index_name = s.segment_name
order by ix.table_name, ix.index_name;