Del Air Rockhounds Club, Inc
The Del Air Rockhounds Club, Inc Los Angeles - San Fernando Valley, California, United States - We are a non-profit organization dedicated to sharing knowledge of the lapidary arts and techniques, geology, mineralogy and related fields.
Monday, December 31, 2012
The Del Air Rockhounds Club Welcomes You!!
Wednesday, May 2, 2012
May 2012 Rock of the Month
Meteorites & Tektites
A meteorite is a natural object
originating in outer space
that survives impact with the Earth's surface. A meteorite's size can range
from small to extremely large. Most meteorites derive from small astronomical objects
called meteoroids, but they are also sometimes
produced by impacts of asteroids. When
a meteoroid enters the atmosphere frictional, pressure and chemical
interactions with the atmospheric gasses cause the body to heat up and emit light
thus forming a fireball, also
known as a meteor or shooting star. The term bolide refers
to either an extraterrestrial body that collides with the Earth, or to an
exceptionally bright, fireball-like meteor regardless of whether it ultimately
impacts the surface. As of February 2010, there are approximately 1,086 witnessed falls having specimens in the world's
collections. In contrast, there are over 38,660 well-documented meteorite
finds. Meteorites have
traditionally been divided into three broad categories:
stony meteorites are rocks, mainly composed of silicate minerals; iron meteorites are largely composed of
metallic iron-nickel; and, stony-iron meteorites contain large amounts of both
metallic and rocky material.


Wednesday, April 25, 2012
May 2012 Program

Our special guest
this month will be Mr. Larry Bradbury. He will be speaking on a very
interesting subject: Meteorites (Rocks from Space). He will bring many of his
collection pieces to the club meeting on Thursday May 3, 2012 @ 7:30 pm and will answer all your questions about meteorites. You don't want to miss this!
REGULAR MEETINGS ARE HELD ON THE 1ST THURSDAY OF EACH
MONTH @ 7:30 PM AT:
NORTHRIDGE UNITED METHODIST CHURCH-9650 RESEDA BL.
NORTHRIDGE, CA 91324
Guests are always welcome at our meetings
and events
Wednesday, April 4, 2012
April 2012 Rock of the Month
Limestone

Limestone is a sedimentary
rock composed largely of the minerals calcite and aragonite, which are
different crystal forms of calcium carbonate. Many limestones are composed from
skeletal fragments of marine organisms such as coral or foraminifera, which is
a species of marine plankton. Limestone makes up about 10% of the total volume
of all sedimentary rocks on Earth. The solubility of limestone in water and
weak acid solutions leads to karst landscapes, in which water erodes the
limestone over thousands to millions of years. Most cave systems are through
limestone bedrock. Limestone has numerous uses, including as building material,
as aggregate to form the base of roads, as white pigment or filler in products
such as toothpaste or paints, and as a chemical feedstock. During regional
metamorphism that occurs during the mountain building process, limestone
recrystallizes into marble.

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