Thursday, January 28, 2016

February 2016 Del Air Calendar of Events

Del–Air Rockhounds Calendar of Upcoming Events
Feb 2016 
04: General Meeting: 7:30 pm in our regular meeting room 
14: Valentine’s Day: Remember your Sweetheart! 
15: President’s Day: 3 Day Weekend…Woo Hoo!  
18: Board Meeting: 7:30 pm at TBD’s home  
General Meeting: Thursday Jan 07, 2016 
The meeting begins at 7:30 pm in our regular meeting room at:
Northridge United Methodist Church - 9650 Reseda Blvd, Northridge, CA 91324 Guests Are Always Welcome At Our Meetings & Events.

Feb 2016 Program: California's Fossil Whale Bone  
 Presented by: Keri Dearborn
You found fossil whale bone on our January field trip, but what kind of whale bone are you really holding in your hand? Club member Keri Dearborn is a naturalist and environmental educator. She has taught marine mammal zoology and participated in local marine mammal research. We'll look at our local fossilized whale bone with an emphasis on its geological and historical significance and we'll connect it to modern whale populations. Are whales more closely related to wolves or deer? Is your whale bone fossil from a predator or prey animal? What makes whale bone easily identifiable from other mammals? California's coast has been populated by whales for millions of years and continues to be home to one of the world's most robust whale and dolphin populations. How is your piece of fossil whale bone a link to the past and the future?                                Emmy Silverman, Program Director
Support our hobby.....attend a local show....
February 12 - 21: INDIO, CA
San Gorgonio Mineral & Gem Society
Riverside County Fair & National Date Festival
82-503 Highway 111
Hours: 10 - 10 daily
Contact: Bert Grisham, (915) 849-1674
February 20 - 21: ANTIOCH, CA
Antioch Gem Club
Contra Costa County Fairgrounds
1201 West 10th Street
Hours: 10 - 5 daily
Contact: Brenda Miguel, (925) 301-6957

February 27 - 28: VALLEJO, CA
Vallejo Gem & Mineral Society
Solano County Fairgrounds,
Mc Cormack Hall
900 Fairgrounds Drive
Hours: 10 - 5 daily
Contact: Dan Wolke, 707 334-2950

March 4 - 6: NEWARK, CA
Mineral & Gem Society of Castro Valley
Newark Pavilion
6430 Thornton Avenue
Hours: Fri & Sat 10 - 6; Sun 10 - 5
Contact: Cathy Miller, (510) 887-9007

March 5 - 6: ARCADIA, CA
Monrovia Rockhounds
Los Angeles Arboretum-Ayres Hall
301 Baldwin Avenue
Hours: 9:00 - 4:30 daily
Contact: Jo Anna Ritchey, (626) 358-1624,
March 5 - 6: VENTURA, CA
Ventura Gem & Mineral Society
Ventura County Fairgrounds
10 West Harbor Blvd.
Hours: Sat 10 - 5; Sun 10 - 4
Contact: Show Chair, (805) 312-8467
Website: www.vgms.or

March 12 - 13: SAN MARINO, CA
Pasadena Lapidary Society
San Marino Masonic Center
3130 Huntington Drive
Hours: Sat 10 - 6, Sun 10 - 5
Contact: Marcia Goetz, (626) 260-7239

March 12 - 13: SPRECKELS, CA,
Spreckel's Veterans Hall
5th & Llano Streets
Hours: 10 - 5 daily
Contact: Karin Salomon, (831) 375-5233

Go to for more show information. 


February 2016 “Something of the Month”  


A thunderegg is a nodule-like rock, similar to a filled geode. Thundereggs are rough spheres, most about the size of a baseball though they can range from less than an inch to over a meter across. They usually contain centres of chalcedony, agate, jasper or opal either uniquely or in combination. Also frequently encountered are quartz and gypsum crystals, as well as various other mineral growths and inclusions.

Thundereggs usually look like ordinary rocks on the outside, but slicing them in half and polishing them may reveal intricate patterns and colors.Thunderegg is not synonymous with either geode or agate. A geode is a simple term for a rock with a hollow in it, often with crystal formation. A thunderegg on the other hand is a specific geological structure. A thunderegg may be referred to as a geode if it has a hollow in it, but not all geodes are thundereggs because there are many different ways for a hollow to form.

Thundereggs are found in flows of rhyolite lava. They form in gas pockets in the lava, which act as molds, from the action of water percolating through the porous rock carrying silica in solution. The deposits lined and filled the cavity, first with a darker matrix material, then an inner core of agate or chalcedony. The various colors come from differences in the minerals found in the soil and rock that the water has moved through.

On March 30, 1965, the thunderegg was designated as the Oregon state rock. While thundereggs can be collected all over Oregon, the largest deposits are found in Crook, Jefferson, Malheur, Wasco and Wheeler counties. The world’s largest thunderegg, a 1.75 ton specimen, is housed by the Rice Northwest Museum of Rocks and Minerals in Oregon.

January Field Trip Report – Fossil Whale Bone Hunt 
Jan 23, 2016 – 12:00 noon @ Refugio State Beach  

It was an absolutely beautiful day at Refugio State Beach. We could not have asked for better weather. There were perhaps 20 surfers and 8 rockhounds at the beach that day. The 8 rockhounds were club members Jeff Dengrove, Chris Ward, Bob Knox, Richard, Emily & Nicolas Haering and guests Iris Delarosa and her friend Marilyn. We all arrived right around noon and immediately went on the hunt. Not only was there a multitude of whale bone to be found but also many marine fossils, agate, petrified palm root, jasper and sea sponge. All eight of us brought lunches and drinks and enjoyed a mid-afternoon picnic on the beach. After lunch it was back to the hunt. Jeff Dengrove drove down the road to check out Gaviota but returned advising the rest of us the beach over there was covered in sand. All 8 of us stayed at Refugio the entire time and did not leave till the sun went down….and all went home will multiple bags of beach found treasures. I think this was the best hunt in the 10 years I have been attending this event.