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.
|Rock Salt-UT||Oil Shale-CO|
|Mica Schist-WY||Garnet Schist-SD|
|ACICULAR -slender, needle like crystals||MYGDALOIDAL A -rock with mineral filled cavaties|
|BANDED -narrow bands of differing colors||BLADED -elongated, flattened crystals|
|BOTRYOIDAL -globular forms like a bunch of grapes||CAPILLARY -hair like crystals|
|COLLOFORM -spherical forms of radiating crystals||COLUMNAR -column like crystal|
|CONCENTRIC -spherical layers around a common center||CONCRETION -minerals formed around a nucleus|
|DENDRITIC -slender divergent branches||DRUSY -a layer of small crystals on a surface|
|FIBROUS -slender fiber aggregate of crystals||FILIFORM -embedded threadlike crystals|
|FOLIATED -easily separated into plates||GEODE - a spherical hollow cavity lined by mineral(s)|
|GLOBULAR -radiating crystals forming small spheres||GRANULAR -composed of grain like crystals|
|LAMELLAR -plate like crystals forming layers||MAMMILLARY-round masses resembling mammae|
|MASSIVE -a mineral w/o distinguishing features or form||MICACEOUS -easily separated into thin sheets|
|OOLITIC -aggregate of small spheres resembling fish eggs||PISOLITIC -aggregate of spheres the size of peas|
|RADIATED -radiating crystal groups||RENIFORM -radiating crystals forming kidney shape|
|RETICULATED -lattice like groups of crystals||ROSETTE- a flowerlike crystal growth of minerals|
|STALACTITIC-conical/cylindrical deposits of minerals||STELLATED -radiating crystals forming circular groups|
|MINERAL||STATE OF AGGREGATION|
|1. Calcite (in Limestone)||Oolitic|
|7. Gypsum var. Satin Spar||Fibrous|
|15. Gypsum var. Alabaster||Massive|
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