Possible Clues:

• Bishop wants a source of quartz for church
• Church built from quartz to a degree
• Sybil's husband and one accountant in church
• St. Peter's, e.g.
• Church compound headed by bachelor
• Quartz, say, laid underneath airline hall
• See 10 Across
• Saint in charge, leading a church
• Colonnaded building
• Vatican City attraction