This introduction is an all-encompassing look at the Earth: how it was formed and how it works. It explores the emerging geological research and explains how new advances in the understanding of plate tectonics, seismology, and satellite imagery have enabled us to begin to see the Earth for what it is, a dynamic and ever changing planet. It introduces the concepts of plate tectonics, continental drift, the earth's structure, and sea-floor spreading.
Our review: "When I came across this little book for the first time in Bookshop Santa Cruz I almost paid full retail for it! I did go straight to the shop and order a bunch of copies. I'm not disappointed. Earth : A Very Short Introduction has become an instant favorite and one of my must have recommendations. Here's a little pocket size book that you can carry with you just about anywhere. It has great coverage of the principles of geology and is presented in a narrative style. This is a fun read, not a dry geological text."
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.
Map identifies locations of: gold and silver, agate, beryl, corundum, epodote, feldspar, garnet, geodes, jasper, nodules, opal, opalized wood, petrified wood, quartz, rhodonite, thunder eggs, topaz, tourmaline, and zeolite.
The BelOMO 10x21mm(.85") triplet loupe magnifier has a viewing area of 0.65 inch (17mm), much larger than the Bausch & Lomb Hastings Triplet Magnifier. The 3 elements making up this achromatic triplet provide a bright and clear view. The 10x power magnification provides the best magnification to depth of field ratio and is the most popular power for a hand held magnifier. The housing and cover are machined metal and coated with a matte black finish and assembled using flathead screws. Belorussian Optical and Mechanical Association (BelOMA), makers of sights for guided weaponry, camera lenses, and other optical components manufacturers these loupes.
We highly recommend this loupe. This is the lens we use all the time.
Each BelOMO loupe we ship is custom treated to prevent the screws from coming loose with usage.
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