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| AURICHALCITE with CACLITE Southwest Mine, Bisbee, Warren District, Mule Mountains, Cochise County, Arizona, USA |
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| Blue Opals |
Monday, November 23, 2015
Aurichalcite with Calcite E Vs Blue Opal
Sunday, November 22, 2015
Digital Elevation Model (DEM) Resolution Enhancement
03Surface Interpolation
This exercise will guide you through a Method to
generate a New finer resolution of a DEM.
1. Add the dem grid to ArcMap. Check if the grid
has a 30 meter cell size and a UTM projection.
2. Enable Spatial Analyst extension From Customize
> Extension.
3. Open ArcToolBox >> Data
Management Tools toolbox / Raster Processing toolset >>Resample.
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| DEM Resample |
We now try to resample the 30
meter DEM to finer resolutions.
First we need to convert the DEM grid into elevation
points.
1. Spatial Analyst Tools toolbox /
Extraction toolset >> Sample.
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| DEM Sampling |
2. Specify dem 30m as the input raster and as the
input location raster, pnt30m_table.dbf as the output, and NEAREST
as the resample technique.
3. From the ArcMap Layer Panel, right-click on
pnt30_table.dbf and select Display XY Data.... Make sure x is in the X field,
y in the Y field, and dem30 in the Z field.
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| DEM Display points |
4. Export the point event data to a shapefile to make
them permanent. select Data / Export Data, and save the output as
pnt30.shp.
5. Use the spatial interpolation techniques to generate
DEMs from the point data set we just created. The first method we use is Inverse Distance Weighted (IDW).
ArcToolbox/Spatial
Analyst Tools/Interpolation.
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| DEM Interpolation |
6. The DEM automatically added to ArcMap uses a
symbology that is difficult to show the subtle variations in the DEM. Change
the symbology of the DEM layer from "classified" to
"stretched". With this display option, the DEM is displayed as a
grayscale map that shows the detail of the terrain.
Converting & Displaying DEM into DTM (Digital
Terrain Model)>>
Saturday, November 21, 2015
Wednesday, November 18, 2015
Tuesday, November 17, 2015
The surface geology of Africa
The map shows the lithological properties of
the surface geology of Africa. Lithology describes the mineral composition and
structure of geological material which is based on rock formation (i.e. whether
it is igneous, sedimentary, metamorphic) and mineralogy (e.g. carbonate,
silicic, mafic). This map is a good proxy for soil parent material as it only
reflects surface conditions and not the underlying bedrock. It should be noted
that the general nature of this map means that at a local level, the conditions
may be quite different to that shown. Other than the terms alluvium (deposited
by water), aeolian (deposited by wind), organic (peat deposits) and colluvium
(transported by gravity), all of which denote recent deposition, the age of
material is not indicated. The preponderance of wind-blown sediments across
Africa is striking as are the volcanic areas.
Monday, November 16, 2015
The Breakup of Pangaea
Pangaea (sometimes spelled Pangea), the most
recent of a series of supercontinents on Earth, formed about 270 million years
ago and broke apart about 200 million years ago. At this time most of the dry
land on Earth was joined into one huge landmass that covered nearly a third of
the planet's surface. The giant ocean that surrounded the continent is known as
Panthalassa.
The movement of Earth's tectonic plates formed
Pangaea and ultimately broke it apart.
Pangaea existed during the Permian and Triassic
geological time periods, which were times of great change. The Permian mass
extinction, which wiped out an estimated 96% species about 248 million years
ago, was a major event during this time.
Saturday, November 14, 2015
Precious Opal with an "eye" effect
07 Precious Opal with
an "eye" effect
Description:Recently, the Wello (Wollo) locality in
Ethiopia has produced some exceptional precious Opal specimens and gemstones.
The highly desirable "Contra Luz" play of color and large
"harlequin" patterning that can be seen in the top gems and specimens
is comparable to the best of Mexican Opals and even resembles color patterns
seen in Australian gems. Opal is one of those minerals that looks as beautiful
and impressive when it is opaque as when it is water clear. The amazing range
of this material (considering the simplistic chemistry) makes it a cool mineral,
and that's saying a lot considering the species does not even have any crystal
form !! This piece features a very attractive section of Precious Opal with a
notable "eyeball" effect that is highlighted by flashes of gold,
yellow, orange, green and blue. Despite the smaller size, this piece has great
color and form, and could end up being a great bargain for one of you lucky
bidders out there who do not have a piece of this material in your collection.
The following was taken from the article on mindat by Jon Young from last year:
"This newly discovered Opal found in the Welo Amhara Regional State
Highland plateau 2.500 – 3.200
meters above sea level of Ethiopia is a new find that is quickly gaining the
attention of the opal community. This opal was the hit of the recent Tucson
international gem show. Welo opal requires a mountain of patience and some
special cutting techniques but the finished result is every bit as stable as
the better known Australian opals. The color is brilliant and rivals any top
grade opal in the world. Most have a brightness level of at least 4 to 5 on the
brightness scale with hot neon multi-color and multiple pattern mix. Welo opal
is not generally classified as contra luz opal although I have seen a few. The
color play is face up and in a lot of cases, as bright in artificial indoor
light as it is in direct sunlight. This opal just loves any light source. This
is hydrophane opal which when soaked in water allows the base color to clear
up...sometimes highlighting the play-of-color, sometimes making it vanish. The
best trait of the Welo hydrophane opal is that when it's dry and polished it
can be one of the brightest opals in the world. From my experience, the Welo
opal is as stable as the best of all that I have cut in the last 10 years. It
can take twice as long to cut a finished stone, but the visual rewards are well
worth the time. Different types of opals require specialty care for the beauty
you enjoy... Welo opal is no different. No chemicals or detergents...If soaked
in water, it will take one to two weeks to completely dry out and return to its
original beautiful state. Do not try and accelerate the drying by any
artificial means. Do not use ultrasonic cleaning for any opals. Gondar and
Wollo (Welo) are not regarded as desert at all – it is on the Abyssinian highland plateau of
Amhara Proper, Amhara Regional State. The Welo opal is found in the same type
of geological formations as the Australian opal. Welo opal is the most stable
opal find in Ethiopia to date. Ethiopian Opals are region specific in character
traits just like Australian opals. The Ethiopian Government does not own any
mines. All land is owned by the government: In Amhara it is administrated by
the Regional State who does not allow mining by others than registered and
licensed farmer co-operatives.
