Download EN CRACK`N OPEN GEODES

EN
CRACK’N OPEN
GEODES
™
• GEODES •
29643-ED507-8-9Geodes-booklet-ENG.indd 1
23/06/15 09.03
Hello, Geo-Kids!
Stefano Piccini
ARE YOU READY TO FOLLOW
MY TYRANNOSAUR BABYREX™ AND I
ON OUR EXCAVATION MISSION?
JOIN US ON A JOURNEY INTO
THE STRANGE WORLD
OF GeodES!
Managing Director Geoworld
Geologist & Paleontologist
Dear Geo-Kids,
Are you ready for an exciting journey
discovering the wonders of Nature?
I have been doing it for 30 years, and I assure you,
this extraordinary adventure brings enthusiasm
and intrigue without limit.
By the end of our adventure,
you will be beginning geologists!
An idea of Stefano Piccini
Written by Stefano Piccini
Edited by Erika Iaconcig
Project and graphic by Geoworld Science and Art Team
Concept and supervision art by RAM
All rights reserved. No part of this booklet may be reproduced or transmitted
in any form or by any means, electronic or mechanical, including photocopying,
without permission in writing from the publisher.
Dr. Steve Hunters® is a registered trademark owned by Geodreams S.r.l.
Copyright © 2015 by GEOWORLD S.r.l.
29643-ED507-8-9Geodes-booklet-ENG.indd 2-3
23/06/15 09.03
Do you know
what a Geode is?
We must first start from
the magma chambers...
When a volcano erupts, it releases the magma that
accumulated underneath it in a vast cavity known as
the magma chamber.
The magma is a mass of molten rocks which contain many
different elements including: aluminum, magnesium, iron,
sodium, potassium, calcium, silicon, and several gasses.
When magma erupts from a volcano, it is known as lava.
After magma and lava cool, they form igneous rocks
(“igneous” is derived from the Latin, ignis, or fire), meaning
“rocks formed by fire.” There are two types of igneous
rocks: effusive (rocks solidified on the Earth’s crust) and
intrusive (rocks solidified below the Earth’s crust).
Magma does not cool and solidify in a homogenous manner
(evenly). Beneath the Earth’s crust, poor heat dispersion
leads to a slow solidification process. As the magma
solidifies, the elements’ atoms organize in “crystalline
lattices” which grow until the rock solidifies, but before
the entire rock crystalizes.
This is why intrusive rocks form big crystals.
Some crystals are truly wonderful, multicolor
and precious, like diamonds!
The combination of gas bubbles and
temperatures can affect the minerals
dissolved in magma, creating strange
objects: like geodes.
When gas bubbles remain trapped in the magma,
one of the most fascinating geological phenomena
occurs: the formation of geodes.
Volcanic stones
Volcanic stones
29643-ED507-8-9Geodes-booklet-ENG.indd 4-5
Stack of small geodes
23/06/15 09.04
A
geode is what remains of a gas
bubble when it stays “trapped”
in the magma.
also occurs in the kitchen: a dense
pudding drips more slowly than a
liquid soup.
Externally, a geode extracted from
basalt or volcanic stone looks like a
stony globe.
An elongated geode forms when
gas bubbles are trapped in quick
flowing magma. If the geode is pear
shaped, the pointed end indicates
the direction of the magma flow.
In contrast, when dense magma
flows slowly over the bubbles, the
geode takes on a spherical form: in
some cases, even perfectly round!
Incredibly, the spherical geodes
look like small planets! Perhaps,
this explains why they were named:
in ancient Greek, the word geode
means “similar to Earth.”
Opening a geode can be like entering
a small and wonderful world made
of shiny crystal, thousands of years
in the making. The word “geode”
applies to both the outer rock and
inner crystals.
Round geodes
A geode’s appearance depends
on how fast the magma flowed
before solidifying.
BASICALLY, A GEODE
IS A “SOLID” BUBBLE,
OR A CAVITY INSIDE AN
IGNEOUS ROCK.
Geode fragments
If magma flowed quickly: the
geode is oval shaped. If magma
flowed slowly: the geode is round
shaped. The density of the magma
determines its speed, the more
liquid, the faster the flow. If you think
about it, the same phenomenon
29643-ED507-8-9Geodes-booklet-ENG.indd 6-7
23/06/15 09.04
But, where do
the crystals
come from?
A
fter a cavity forms inside magma, water
gradually seeps through the surrounding
rocks.
This water may come from an underground
aquifer or thermal (volcanic origin)
source. In any case, the water contains
dissolved minerals. One such
mineral, silicon, the most
abundant element on
Earth after oxygen, is
the main component of
crystalline rocks.
Agata slice
Silicon deposits itself into the empty
space of the bubble, forming a layer
on the walls (a little like limestone in
an old dishwasher). Usually, the first
layer is compact quartz or matte,
bluish agate called chalcedony in
mineralogy.
Over thousands of years, crystals grow on this first layer
and eventually fill the entire geode.
Really, it’s a mineral version of the Easter egg! Sometimes
only a few inches in diameter, but in some cases, reaching
larger dimensions.
JUST THINK, SOME GEODES
ARE REAL CAVES (LIKE THE
BIGGEST ONE EVER FOUND,
CRYSTAL CAVE IN OHIO),
AS DEEP AS 33 FEET!
The types of crystals grown inside these amazing rock
spheres vary. Amongst the most common are: quartz,
zeolites, carbonates, and sulfates.
Crystal formation depends on both chemical composition
and fluid temperature (from 1562 to 122
Fahrenheit) of the liquid which soaks
through the surrounding rock.
The most beautiful geodes are
contained in quartz.
Okenite
29643-ED507-8-9Geodes-booklet-ENG.indd 8-9
23/06/15 09.04
Quartz is one of the most common minerals of the Earth’s
crust and is frequently found in igneous rocks. Quartz is
easily recognizable because it looks like a hexagonal
prism.
Quartz is one of the main materials used to make
glass. It has many chemical and physical properties,
like: durability, heat resistance, and electrical
polarization. Quartz‘s characteristics lend to
use for many electronic tools like quartz
watches, radios, and digital instruments.
Halogen bulbs and many scientific
instruments (especially optics) are also
made of quartz.
Since ancient times,
the most precious
specimens are cut to
create gems for
jewelry.
One of the most beautiful varieties of quartz found in
geodes is amethyst.
Amethyst is often present in volcanic rocks; accumulated
in small pyramidal clusters. It is commonly used in jewelry
for its brightness and characteristic purple color which
comes from traces of iron. Legend has it, Amethyst was
a beautiful nymph that the God Bacchus loved. Bacchus
gave Amethyst his favorite color, the color of wine, as a
token of his love.
The geodes that contain amethysts are most valuable
and, therefore, the most sought after.
Another mineral that is typically present
in geodes is calcite, whose crystals
compose three-sided, colorless or
delicately colored prisms; these have
a slight fluorescence and are often
grouped in extraordinary heart or
butterfly-like formations!
Other minerals than can appear in
the form of crystals inside the
geodes are pyrite, dolomite,
celestite, limonite and opal.
Amethyst geode
Celestina geode
29643-ED507-8-9Geodes-booklet-ENG.indd 10-11
23/06/15 09.04
G
eodes can be found all over the world, as expected,
there are greater concentrations in volcanic areas
and deserts.
Rarely, geodes form in sedimentary rocks, or rocks formed
slowly from an accumulation of debris, mud and other
sediments.
Iron, cobalt, nickel, and most frequently manganese
nodules are common on the ocean floor. Many nodules
contain the same multicolor characteristics of minerals
found in geodes: such as agate, chalcedony and jasper.
The essential difference between a nodule and a geode
is that the first is totally compact, without empty spaces,
while the second is hollow.
The most spectacular geodes come from Brazil, but there
are geode deposits in Namibia, Mexico, and other North
American countries too.
SUCH BEAUTIFUL GEODES
WERE FOUND IN IOWA
THAT THE STONE BECAME
THE STATE’S SYMBOL.
Similar to geodes, nodules are geological formations
containing crystals. A nodule is less attractive then a
geode because of its irregular shape. Basically, any
mineral formation with a difference between the outside
and inside composition is called a nodule. Nodules could
be a mineral like pyrite wrapped in a block of carbon, or
crystals surrounded by a lump of fossil sediment.
29643-ED507-8-9Geodes-booklet-ENG.indd 12-13
23/06/15 09.04
P
atience is essential to keep the geode intact when
opening the rocky sphere.
FASCINATING,
DON’T YOU THINK?
NOW, IT’S YOUR TURN TO
CONTINUE THE MISSION;
THERE’S A NEW DISCOVERY
WAITING!
The bigger the pieces, the easier to admire the crystals.
Ideally, you try to divide each geode in half, like a big nut,
in order to preserve them in your collection.
Geode
section
You
must
be
ready
for
disappointment. Often, geodes
are completely hollow with no
crystals inside. Discovering
an empty geode can leave a
bitter expression on the face
of any aspiring geologist…
this has happened to me more
than once!
Indeed, no one knows what’s inside a
geode until opening it...
Therefore, it’s best to carefully hit the geode.
If the geode is empty, a hard blow from a hammer could
break it into dozens of pieces that fly in all directions.
Insights and
fun facts on
:
www.drs
tevehunt
ers.com
printed in China
29643-ED507-8-9Geodes-booklet-ENG.indd 14-15
23/06/15 09.04
WONDERS OF NATURE
™
USA LLC
Tucson, AZ
Ph. +1.520.884.4867
[email protected]
www.geoworldusa.com
ASIA LTD
Kowloon Bay, Hong Kong
Ph. +852.3543.1890
[email protected]
www.geoworld.asia
www.drstevehunters.com
www.geoworldgroup.com
29643-ED507-8-9Geodes-booklet-ENG.indd 16
29643
S.r.l.
33040 Torreano (UD) - Italy
Ph. +39 0432 715611
[email protected]
www.geoworldgroup.com
23/06/15 09.04