Derived from the world-renowned McGraw-Hill Dictionary of Scientific and
Technical Terms, Sixth Edition, this vital reference offers a wealth
of essential information in a portable, convenient, quick-find format. Whether
you're a professional, a student, a writer, or a general reader with an interest
in science, there is no better or more authoritative way to stay up-to-speed
with the current language of geology and mineralogy or gain an understanding
of its key ideas and concepts.
Written in clear, simple language understandable to the general reader, yet
in-depth enough for scientists, educators, and advanced students, The McGraw-Hill
Dictionary of Geology & Mineralogy, Second Edition:
Minerals of the World is an attractive and up-to-date guide to more than 500 minerals from around the world. The succinct text--covering crystallography, properties, names and varieties, structure, diagnostic features, and occurrence--and the discussion of less common minerals not found in other guides make this an invaluable resource. With over 600 exquisite color photographs and crystallographic diagrams, this book is unequalled. It is set to become the field guide of choice for mineral collectors and students of mineralogy.
The Mineral Hardness Ruler is a stimulating visual aid, educates in one phase of mineralogy, and provides the standard ruler measurement scales needed in classes.
Rockhounds, mineral enthusiasts, students, teachers, geologists, and any one interested in rocks and minerals will find the Mineral Hardness Ruler a handy visual aid for quick information on mineral hardness.
The two-sided, flexible, glossy, vinyl ruler consists of five scales: three measurement scales and two mineral hardness scales. The measurement scales are in standard ruler measurements of tenths of inches, sixteenths of inches, and millimeters. Mohs' relative hardness numbers are integrated into the inch scales, while a separate scale exists for an absolute mineral hardness scale by Rosiwal.
On one side of the ruler are pictures of the ten common minerals, in full color, selected by Mohs for his relative hardness scale. On the reverse side of the ruler are six common items with their relative hardnesses. These items, along with known minerals, can be used as a handy field kit to test the relative hardness of an unknown mineral.
Hardness is one property of a mineral that can be used to distinguish among similar minerals. A given mineral can scratch any other mineral of the same or softer hardness. Over a hundred years ago, the German mineralogist Frederick Mohs devised the relative hardness scale that has found favor with mineralogists for over a century. Others, such as Rosiwal, formed absolute hardness scales using the same minerals as Mohs. For example, diamond, the hardest substance in Nature is not twice as hard as apatite, 10 versus 5, but over twenty thousand times as hard, 140,000 versus 6.5.
The Raytech Tumble-Vibe 5 Vibratory Tumbler (Model TV-5) is economical and versatile.
Thousands of satisfied customers testify to the durability and simplicity of the Tumble-Vibe 5. Mated with a spare bowl, and a GSH-2 Stone finish Kit, the new TV-5 Starter Kit is a must for any beginner.
This new kit comes complete and ready to operate with a motorized base, two bowls, clear lid, 2 rubber nuts and all the grits necessary for accomplishing the grinding step through the final polish step of most gemstones. The (4) steps that are included are Silicone Carbide (100/1200) Silicon Carbide (700F), Iolox 50, Raybrite TL (GS-H2 Stone Finish Kit for hard rocks and minerals). There's enough grit for 8-15 pounds of stones. This new compact system will handle a myriad of applications. (Polished stones for illustration only. They are not included with this tumbler.)
Check out this article on Vibratory Tumblers
This popular low-cost unit is a favorite of the hobbyist and is used commercially as well. Vibrating rock tumblers process rocks 5 times faster than rotary rock tumblers. See results in days rather than weeks! This vibrating rock tumbler will process about four pounds of rock in it's .05 cu ft (3 pint) bowl. Bowl diameter is 8" and has a new convenient solid lid system. Shipping weight is 12 lbs., 1.05 cu. ft.
The BelOMO 20x Quadruplet Loupe Magnifier has a viewing area of .28" (7mm), much larger than the Bausch & Lomb Hastings 20x Triplet Magnifier. The large .5" (17.5mm) 4 elements gather lots of light to provide this quadruplet loupe with a bright and clear view.
The following details are true of any lens such as a loupe magnifier, microscope, telescope, camera lens or other high magnification lens.
A 20x magnifier should NOT be the only magnifier you own. It's just too much magnification for normal usage. For instance, if you're using it to look at newsprint you would see at most a 4 letters at a time.
Must you have such strong magnification?
You'll be incredibly close to the object you are examining. Almost touching. For a 10x the focus distance is around 3/4'' but for a 20x it's about 5/16''.
The 20x power magnification provides a very strong level of
magnification which works best on flat objects like coins or stamps or surfaces of objects.
However, only a small area (field of view) will be visible. Think of examining a quarter and all you can see is the date but it's highly magnified.
The stronger the magnification means the less depth of field the lens will have. Depth of field is the vertical relief that appears in focus on an object having an irregular surface like a rock or mineral. You'll have to ''dance'' the lens around more on rocks and minerals but the portion of the object you're viewing will be highly magnified. The limited depth of field also make a 20x the most magnification you'll want to use when hand holding a loupe. With a higher magnification the slightest movement in you hand will cause the image to continually move in and out of focus.The high magnification works well when you need to closely examine the surface of a rock or mineral, the surface of a gem for minute scratches, small areas of coins and stamps or any other object where you need to examine a small area under high magnification. It's great for reading laser inscriptions on diamonds.
The larger size of this lens compared to other 20x loupes means it will capture lots of light for a very bright view. This is also a loupe that you can hold comfortably in your hand unlike the smaller than a dime lens from Bausch & Lomb.
The housing and cover are machined metal and coated with a matte black finish and assembled using flathead screws. Belarusian Optical and Mechanical Association (BelOMA), makers of sights for guided weaponry, camera lenses, and other optical components manufacturers these loupes.
Highly recommended by the Amateur Geologist. The BelOMO loupes are the loupes we always use though it's the 10x that we typically carry in the field. If you MUST have 20x power then this is a great lens to have.
Don't let this price fool you. The BelOMO loupe is a FANTASTIC buy. These are quality lenses that stand on their own against the higher priced competition. Take advantage of the recovering Belarus economy and a military supplier finding other revenue streams in a capitalistic market.
Each BelOMO loupe we ship is custom treated to prevent the screws from coming loose with usage.
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