This article describes two forms of Gemstones: Agates and Jasper

1. GEMSTONES
Agate &
Jasper- The chalcedony minerals
By - Fashagba, Imoleayo M.

2. Have you used or heard people using the words – ‘you’re such a
gem’, ‘that’s a gem of car’? So, what is a gem? The Merriam-
Webster dictionary defines gem to be something or someone
highly prized or well beloved. So, one could think of Gemstones as
‘stones that are gem’.
In geology, Gemstones (also called gem) are rare minerals, organic
matter or rocks that are highly prized for their quality or beauty
and can be cut into specifications to make jewelry and decorative
items.
Gemstones have two common classification. It can either be
classified into two groups or generally into one. The former are said
to be either precious or semiprecious stones. There are five
recognized group of precious stones, these are: Diamonds, Ruby,
Sapphire, Emerald and Opal while others are said to be
semiprecious. The latter are defined on the basis that gemstones
are usually rare or limited in supply, because of this all gemstones
can be said to be precious.
This article focuses on describing two gemstones: Agate and Jasper.
This is commonly found around the Pacific Coast of Oregon. These
two gemstones are classified as Chalcedony minerals. Chalcedony
minerals are oxides with a microcrystalline quartz (SiO2) (this means
that the quartz crystal structure are small and can only be seen
through a microscope). Sometime you can find people using the
word cryptocrystalline interchangeably for the word
microcrystalline. More specifically Chalcedony minerals are defined
to be a group term for a waxy (gel), smooth form of quartz (i.e.
microcrystalline or cryptocrystalline) often lining or filling cavities
and voids in rocks. The different minerals under the Chalcedony
group are differentiated mainly through their diaphaneity or
transparency.
There are three major forms of transparency. These are: Transparent
(light and images can be seen through), Translucent (only light can
be seen through) and Opaque (no light passes through).
The color of Chalcedony minerals are highly variable. Basically, it
could be white, blue, green, red, brown or black. It sometimes
occur in other colors. On Mohs scale of hardness, Chalcedony
minerals have a hardness of 7. They are very hard materials and
their characteristics enables it to be cut and polished into the
beauty that we so much cherish. This is why we refer to them as
Gem or Gemstones.
Overview
“This article
focuses on
describing two
gemstones:
Agate and
Jasper. This is
commonly
found around
the Pacific
Coast of
Oregon”

3. What is an Agate?
How does Agates Form?
Agates are simply semitransparent to translucent
microcrystalline quartz or more conveniently can be said
to be semitransparent to translucent Chalcedony. Their
mode of formation results into a ‘bandy’ nature of the
mineral. These bands are displayed as variety of colors
(this is as a result of impurities). The colors are what
define or reveal the gem in Agates. The band in Agates
may be wavy or parallel from differences in deposition.
Agates typically forms in igneous rocks such as basalt, rhyolite and sedate or
sedimentary rock such as limestones. The process of Agate formation starts when lava
forms and flow over time on each other. At the top of the layer of lava, there are pockets
called vesicles or voids. The voids are empty and serve as passage way for water to go
through. The water in this region usually contains high amount of silica. The silica
present in the water are dissolved to become silica gel, then the gel slowly crystallize to
form microcrystalline quartz.
There is a continuous layering of the microcrystalline quartz as a result of continuous
lava flow, The end product displays as bands with different colors; the color comes from
impurities present in the water.
Pictures of beach Agates found around port oxford on the southern
Oregon coast
Mexican Laguna Agate

4. What is Jasper?
How does
Jaspers Form?
Jasper is an opaque microcrystalline quartz usually
red, yellow, brown or a mixture of these color,
sometimes Jaspers can be banded.
The transparency of Agate is what differentiates it
from Jasper. As earlier noted, the different colors
are as a result of impurities in the stone.
When Jasper is dull and lacking colors or patterns,
it is called Chert (Compact form of Chalcedony
typically found as nodules or aggregates of tiny
crystals in sedimentary rocks).
Jasper is commonly an expensive gemstone when
used in jewelry, it can be used as necklaces and
bracelets or carved to be worn as a pendant.
Jasper forms majorly in the presence of pyroclastic
or volcanic ash by recrystallizing them into
microcrystalline (cryptocrystalline) quartz. This
aforementioned process produces silica rich
mixture which then cements the sediments into a
solid mass. The presence of impurity during this
process gives Jasper its color and opacity. The
varying sediments and ash are what gives jasper its
many colors and patterns.
Red Hermite Jasper
Jasper
Agates and Jaspers are one of best Gemstones. They come in various varieties as a
result of their different colors. These precious stones can be found around us and be
greatly utilized for human benefits.