Here is a spectacular and informative guide to the amazing world beneath our feet. Stunning color photographs of rocks, fossils, minerals, precious metals, crystals, jewels and gemstones give the reader a unique eyewitness insight into the evolution and composition of the Earth. See rocks that have come from outer space, stalactites as old as dinosaurs, the strange and beautiful shapes of natural crystals and priceless nuggets of gold, silver and platinum. Learn what the Earth is made of - and how its rocks were formed, how early humans made the first flint tools and how diamonds and precious stones are cut, polished, and made into jewelry. Discover how prehistoric animals are preserved today as fossils, how volcanoes work, how rocks are formed from molten lava, how minerals and metals are mined and how pebbles on the seashore are worn down into sand, and much, much more!
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.
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