Goldmine

A source containing an unusually rich supply of valuable information, ideas, or opportunity.

Reach for it when describing abundant potential while making clear what the value consists of

The oral-history archive is a goldmine for local researchers.

• playful

  bonanza

  a sudden abundance or commercial gain creates excitement

  not when Bonanza suggests a windfall and fits poorly for value requiring years of work.

• playful

  mother lode

  the source seems to contain the main concentration of value

  not when Mother lode is mining slang and can sound clichéd or speculative.

• everyday

  windfall

  unexpected benefit arrives with little prior planning

  not when A goldmine may demand sustained extraction, unlike a windfall.

• warm

  treasure trove

  many valuable discoveries are already present

  not when Treasure trove is decorative language and may overstate routine records.

• professional

  rich source

  measured prose should identify abundant useful material

  not when Rich source is accurate but lacks the exceptional promise of goldmine.

• formal

  trove

  a collected store of valuable objects or information is meant

  not when Trove implies a discovered collection rather than an ongoing opportunity.

• literary

  reservoir

  stored abundance can be drawn on over time

  not when Reservoir suggests capacity but not exceptional worth.

• dead end
• barren source
• money pit

• goldmine of information

  The annotated catalog is a goldmine of information for conservators.

• data goldmine

  The survey could become a data goldmine if consent and access remain clear.

• potential goldmine

  The neglected seed bank is a potential goldmine for climate research.

Goldmine is metaphorical and does not prove financial value. Name the valuable material or opportunity.