RAINBOW’S END — Technical Notes 

Claim type: Placer (historic district with widespread placer gold; nearby lode occurrences)

County/State: Mineral County, Montana

Township/Range/Section: T15N R28W, West Half of Section 13 (Public Land Survey System)

Physiographic province: Northern Bitterroot Range / Clark Fork watershed

Land status context: Area is within/adjacent to the Superior Ranger District (Lolo NF) and historic Cedar Creek–Oregon Creek placer fields. Historic dredge tailings remain along Oregon Creek, evidencing district-scale placer production in the early 1900s and again circa 1930–1935. 

District & Location Context

• Cedar Creek–Oregon Creek Goldfields (Superior area): The district has produced placer gold since the late 1860s, with successive waves of activity and later mechanized re-working/dredging. It remains one of Mineral County’s signature placer belts.  

• Near-by named workings: Yellow Bucket Placer and “Upper Oregon Gulch Placer” are recorded in the same township-range block (T15N R28W) around Oregon Gulch/Oregon Creek, underscoring active auriferous gravels and modern claim interest.  

Access & Logistics 

• Primary access hub: Town of Superior, MT (services, fuel, accommodations). From Superior, historic workings are reached via the Cedar Creek Road network; Oregon Creek/Missoula/Bonanza Gulch forks spur from this system. Final approach varies by specific monument positions within W½ Sec 13, T15N R28W. (Field-verify current road conditions; seasonal gates and storm impacts can affect access on Lolo NF roads.)  

Established road corridors plus visible historic tailings in the broader Oregon Creek drainage reduce exploration risk and mobilization costs compared to greenfield sites. 

Topography, Elevation & Drainage

• Relief: Steep V-shaped gulches draining east off the Bitterroot crest toward the Clark Fork.

• Drainage focus: Oregon Creek/Cedar Creek system with multiple gold-bearing tributaries (Bonanza, Missoula, etc.). Spawning-habitat surveys recognize Oregon Gulch/Cedar Creek as sensitive native-fish waters—important for timing and best-management practices.  

• Implication: Placer targets are in modern/alluvial channel gravels, bench gravels, and possible relief floodplain bars; careful water-quality BMPs will be required.

Geology & Mineralization Model

• Deposit style: Placer gold derived from erosion of quartz-vein/lode sources in the Bitterroot metamorphic and intrusive terranes, reconcentrated in gulch and bench gravels. Reworking by historic bucket-line dredge operations confirms economic grades over channel-length scales elsewhere in the immediate drainage.  

• Nearby named placer occurrences: Yellow Bucket Placer (Mineral County; ~4,879 ft elev.) and Upper Oregon Gulch Placer (noted as possibly the same locality) indicate persistent coarse/fine gold in this block.  

• Exploration emphasis for Rainbow’s End:

  • Modern thalweg gravels & tight meanders (pay streak traps).

  • High benches and inside bends with compacted, iron-stained “blue/gray” gravels.

  • Residual colluvial aprons below quartz-vein ridges.

  • Contact zones where gradient changes flatten and trap heavies.

  • Historic Workings & Evidence of Production

• District-scale production indicators: Documented dredge tailings on Oregon Creek (early 1900s and 1930–1935 campaign). Presence of tailings demonstrates sustained gold grades at the channel scale within the same drainage network serving the claim’s section.  

• Recorded operations near T15N R28W: Multiple MRDS/registry records (Yellow Bucket, Upper Oregon Gulch Placer) corroborate long-term activity.  

6) Environmental & Regulatory Considerations

• Jurisdictional backdrop: Lolo National Forest (Superior RD) with state and federal overlays (DEQ water quality). Any in-stream work will require coordinated permits and seasonal timing restrictions.  

• Water quality context: Cedar Creek/Oregon Gulch sections support native trout (bull trout, westslope cutthroat). BMPs for sediment control (sediment basins, silt fencing, progressive reclamation) are essential to secure NOI/POO approvals. 

• (Note: The latest USFS reported bull trout were not present within the area of the Oregon Gulch Project. - Dredging is still allowed under an authoriszed 310 Joint Dredge Plan of Operationms. However,, the same study resulted in all dredging denied in the Cedar Creek Drainage.) 

7) Recommended Work Program 

Phase I – Rapid Assessment (2–4 field days)

• Traverse and GPS the claim corners/monuments across W½ Sec 13; record active channel/bench features and legacy workings.

• Panned concentrates every 100–150 ft along thalweg & bench test pits; classify to ⅜” and pan; retain cons for micro-sluice verification.

• Metal detector sweeps on bench lag gravels for coarse pieces/ironstone indicators..

Phase II – Test Pitting & Bulk Samples

• 10–20 excavator pits to compact/false-bedrock; channel cross-sections at inside bends; target pay streaks indicated in Phase I.

• Collect 0.5–1.0 yd³ composites per pit for small wash-plant recovery tests (document feed, tails, and cons weights).

• Screen for gold particle size distribution to guide plant selection (sluice vs. trommel w/ expanded riffle geometry).

Phase III – Pilot Plant & Grade Control

• Deploy 10–30 yd³/hr mobile plant on highest-priority bars; run production-scale tests with tight mass-balance logging.

• Establish cut-off grade and strip ratios; compile economic sensitivity (gold price, fuel, labor, rehab).

• Concurrent reclamation trial plots (re-grade, woody debris, seed mixes) to demonstrate stewardship for permits and investors.

8) Sampling & Assay Guidance

• Channel sampling: vertical channel samples to compacted layer/bedrock; record lithologic contacts and clay lenses.

• QA/QC: duplicates every 10th sample; spiked blanks on pan-con fire assays; chain-of-custody maintained.

• Reporting: grams/m³ and oz/yd³ with recovery curves by size fraction.

9) Why Rainbow’s End

• Proven district: Documented dredge tailings and multiple recorded placer occurrences in the same township-range block—clear evidence of system-scale gold endowment.  

• Low entry risk: Road access via established forest routes; near town services in Superior.  

• Multiple targets in one claim: Modern channel, benches, and relict bars allow staged development and quick scaling once pay streaks are delineated.