RIALTO BEACH
north of La Push, Clallam County, Washington, USA

LOCALITY IMAGES


GEOLOGY
Basalts from the interior of the Olympic peninsula host manganese ore with associated jasper and agates. Orbicular jasper is common, with jasper is in the form of small spherules (orbicules) commonly found with manganese minerals interstitial to the orbicules. This combination makes for a very aesthetic rock that takes a wonderful polish. Specimens of this material have been carried by rivers from the peninsula's interior to the beaches along the Washington coast, where they have been naturally rounded by wave action.

Rialto Beach is an entry point for over 50 miles of wilderness coastline to the north. Contact the Olympic National Park Visitors Center for collecting status. Also, information about beach combing along the Olympic National Park wilderness coast can be found on the National Park Sevice website.

MINERALS

*Almandine-
Fe2+3Al2Si3O12 - Found as sub-millimeter sized pink to red sand grains, concentrated in streaks along the beach.
*Pyrolusite-
MnO2 - Found interstital to jasper orbicules (described below), likely associated with other manganese oxides. Dark gray, with a metallic luster when polished.
*Quartz- SiO2 - (Var. Jasper) - Jasper forms concentrically banded orbicules to about 1 cm in diamter. Orbicules are predominately red, with bands of yellow, orange, green, and white.

* photographed
 
QUARTZ (Var: Jasper) -
orbicular jasper
 
QUARTZ (Var: Jasper) -
orbicular jasper,
tumble polished
 
QUARTZ (Var: Jasper) -
orbicular jasper,
cut and polished
 
QUARTZ (Var: Jasper) -
orbicular jasper,
cut and polished


 
ALMANDINE- and MAGNETITE-bearing sand
 
Interstital manganese oxides (PYROLUSITE)
with
QUARTZ (Var: Jasper) -
orbicular jasper,
cut and polished