Shopping for Collectibles? Youโve come to the right place.
With nearly 3 million items in our catalog, Bonanza is your destination for Art & Collectibles. Discover rare,
unique, and vintage goods you wonโt find anywhere else.
(It may be possible to pay only $18.69 instead of $21.00 when you
use your bCredits at checkout)
Sign up and get $5.00 bCredits free to use at checkout and another $5.00 bCredits when you make your first purchase.
More info
To learn more about bCredits, please click again on the icon or click here
Share & earn! Sign in, share this or any listing, and youโll get commission when it sells.
Learn more
Returns accepted for 90 days. Buyer pays all shipping expenses in both directions.
If the returned item is a geiger counter, then it must be in the same working condition as when received. The fragile PROBE can be damaged by thin air at high altitude in a plane, so return shipping must be GROUND ONLY.
Returns accepted for 90 days. Buyer pays all shipping expenses in both directions.
If the returned item is a geiger counter, then it must be in the same working condition as when received. The fragile PROBE can be damaged by thin air at high altitude in a plane, so return shipping must be GROUND ONLY.
Natural Uranium Ore
COFFINITE
Weight: 7.7 oz. Radiation: 23,200. CPM (counts-per-minute)
$21.00 plus $12.80 shipping
This rock was collected during July 2025 at
Jurassic Canyon, 18 miles NW of Grants NM.
This rock has TWO WHITE DOTS, which
identify the two surface locations with the
strongest response of radioactivity.
ACCURACY OF MEASURED
RADIOACTIVITY LEVELS
Every rock has a radiation number labeled on
top of the metal foil wrapper. My own
measurements are HIGHLY ACCURATE. Each
measurement has been done with a LUDLUM
2200 GEIGER-SCALER. This is the most
accurate radiation measuring device available to
hobbyists like you and me. I have THREE
Ludlum 2200 geiger-scalers; two are shown in
the attached photos, and a third was
purchased as a spare. One was calibrated by
geiger expert Tom Hall (RADINC; based at
Stewart, Florida); I adjusted the other two.
They are highly accurate because a geiger-
scaler instrument actually counts every tick,
then shows the count-total on a six-digit
digital screen, as you view on the attached
color photos.
DO A "CAVEMAN CALIBRATION"
ON YOUR OWN GEIGER
"Its so easy, even a caveman could do it."
Here's how: Every rock I ship to buyers has a
label on it, showing the measured CPM geiger
response. Remove the metal foil, then measure
the white dot on each rock. If YOUR
MEASUREMENT differs from the number on
my label for that rock, then ADJUST THE
RANGE-LEVELS on your own geiger. Every
Ludlum, Bicron, or other classic geiger has
three or four range-adjuster potentiometers.
For each measured rock, choose the range-
adjuster that has the labeled value in the
center of its displayed range on the meter. If
you can get your measured radiation value very
close to the value written on the gummed label
that came with the purchased rock, then your
instrument has had a "caveman calibration." I
round the measured values to the nearest 500
cpm value, which is accuracy within 5%.
On the web, the biggest "geiger calibration
rip-off" is a vendor ad that solicits a
calibration service on the yellow civil-defense
geigers from the 1960 cold war, for those
CDV-700 units. In the ad, the vendor offers a
calibration service for about $90.00 when the
geiger is mailed. Yet, the printed owners
manual for the CDV-700 civil defense geiger
has A SINGLE PARAGRAPH that instructs the
user how to use the attached "cesium check
source" on the right side of the metal case to
do a simple calibration, merely by adjusting a
single potentiometer, located on the geiger's
internal circuit board. I will happily send a
photocopy of that self-calibration paragraph;
just mention that you want the photocopied
self-calibration for the CDV-700, when you
buy a uranium rock from me. It will then be
enclosed with the purchased rock being mailed.
Stephen Buggie, Ph.D.
"Have geigers, will travel."
Professor Emeritus
Univ. of New Mexico, Gallup