Camp Hycliff, Malheur County, Oregon, USAi

Regional Level Types
Camp Hycliff	Occurrence (Uncertain)
Malheur County	County
Oregon	State
USA	Country

Date: April 29, 2025

Location: This locality extends for about twenty-five metres along the eastern shoulder of Owyhee Lake Road. It is north (downstream) of both Owyhee Dam and Lake Owyhee.

Coordinates: The center of the collecting area is at: 43.662239, -117.255475.
The north margin of the collecting area is at: 43.662425, -117.255356.
The south margin of the collecting area is at: 43.662019, -117.255439.

Host Rock: The deposit is a mixture of a number of discrete basalt flood basalt flows (locally but rarely amygdaloidal), with minor interlayered sedimentary deposition, occasional aeolian ash horizons, and very scarce alluvial/fluvial detritis. Much of the basalt shows surficial oxidation.

Mineral Species: At present, only the two zeolite species heulandite-(Ca) and stilbite-(Ca) have been identified. These species are present as microcrystals reaching a maximum of 0.5mm. They are thickly clustered within very small voids and along their margins, of what appears to be a welded aeolian tuff composed of ash particles and altered debris. Calcite may be present (as evidenced by weak matrix reaction with dilute hydrochloric acid), but so far no discrete crystals have been seen . A few tiny spots on both the zeolite crystals and the matrix are fluorescent pale-blue under the long-wave (365nm) ultraviolet lamp, which may indicate late-stage opal deposition. The black dendrites are probably manganese oxides, but have not yet been confirmed as such.

Author: Jon Gladwell

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