W004 / Oregon

Richardson / Priday thundereggs

A group of named beds · not one uniform material

The outside is only the wrapper. A thunderegg’s cut face reveals its filling, but “Priday” should not erase the name of the bed it came from.

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Priday Blue Bed thunderegg agate — source-labelled reference specimen
Priday Blue Bed example within the Richardson / Priday thunderegg group; not representative of every bed.

James St. John · CC BY 2.0 · No changes

Source-labelled Priday Blue Bed specimen. Do not use this image to identify South Blue, Red Bed or Pony Butte material.

Image source and provenance · License

What it is

Nodules associated with rhyolitic volcanic material, with later mineral filling. Thunderegg describes a structure; it is not a mineral species or a promise of an agate-filled center.

What to look for

A cut nodule may show a contrasting outer body and patterned interior. Fillings, voids and color vary. Do not identify a particular bed from the most familiar color combination alone.

At the cutting bench

Whole rough, cut halves and polished faces are different products. The saw direction changes the view. Keep both halves and the original bed label together when possible; look for cracks before paying to cut an egg.

Under the loupe

Compare outer rock, interior structure and verified bed examples together. Similar eggs occur at other western localities. A photograph cannot reliably assign an unlabeled half to Priday, much less to one Priday bed.

Source & collecting access

VERIFIED OPERATOR STATEMENT — public digging is permanently closed. The ranch says it continues to sell freshly dug material from named beds. Store access and purchase are separate from permission to dig; production quantity and schedule were not independently verified.

Status checked September 2026

The market notebook

Market data insufficient for a reliable range. The operator posts Priday rough at US $3 per pound and small Opal Bed eggs at US $5 per pound. These are posted asking prices for different stock, not confirmed sales or values for exceptional polished halves. Rough is not shipped.

Market researched 30 September 2026

Open the field notes

Names, labels & aliases

Priday agate beds; Richardson Ranch thundereggs. The operator separately names South Blue, Red, Pony Butte, Opal, Priday Moss and Old Beds 1 and 2. Keep these as bed-level names, not interchangeable aliases.

How it formed

Geological studies distinguish the formation of the volcanic nodule from the later minerals filling its spaces. The ranch’s popular explanation is useful context, but a simple gas-bubble story does not capture every thunderegg’s development.

The collecting story

The Priday beds remain part of the ranch’s named identity. Detailed discovery dates and the production history of individual beds have not yet been verified against original documents. No tribal origin story is repeated without a traceable cultural source.

Reading an old-stock label

Public digging closure does not make all available material historic stock. The operator explicitly says it continues to carry freshly dug eggs. Keep a collecting date separate from a purchase date.

What we know—and what we don’t

VERIFIED: operator’s public-digging closure statement and posted prices. WELL SUPPORTED: thundereggs have a volcanic body and later filling. UNKNOWN: exact bed provenance of an unlabeled egg and detailed production chronology.

C&C Reference Collection

No C&C reference specimen has been authenticated for this record yet. Acquired in Oregon is not the same as formed in Oregon. Preserve an estate’s original wording and mark any lost locality documentation.

Sources & Further Reading
  1. Richardson’s Rock Ranch · operator statement

    Direct operator evidence for public digging closure and continued freshly dug stock; no independent production-volume audit.

  2. Richardson’s Rock Ranch · Rock Prices

    Posted asking prices, per pound unless noted. Rough is not shipped; subject to change.

  3. New Mexico Bureau of Geology · Rockhound State Park geology

    Independent explanation of thunderegg structure and separate formation processes; not a description of every Priday bed.

  4. CDC/NIOSH · Safe Work Practices for Silica

    Dust control guidance; wet methods are one control, not a guarantee of safe exposure.

Silica-bearing stone can release hazardous dust when cut or ground. Use appropriate dust controls; wet working alone is not a safety guarantee.