|
|||||
|
Group E. -Stones whose specific gravity lies between 2.50 and under 3.000. Phenakite 2.965 Turquoise 2.800 Beryl 2.709 and occasionally to 2.81 Aquamarine 2.701 ” 2.80 Labradorite 2.700 Emerald 2.690 Quartz 2.670 Chrysoprase 2.670 Jasper 2.668 Amethyst 2.661 Hornstone 2.658 Citrine 2.658 Cordierite 2.641 Agate 2.610 Chalcedony 2.598 and occasionally to 2.610 Adularia 2.567 Rock-crystal [...] The fixing of the specific gravity of a stone also determines its group position with regard to weight; its colour and other characteristics defining the actual stone. This is a safe and very common method of proving a stone, since its specific gravity does not vary more than a point or so in different [...] Though the origin, formation, composition, characteristics and tests of each stone will be examined in detail when dealing with the stones seriatim, it is necessary to enquire into those particulars of origin which are common to all, in order thoroughly to understand why they differ from other non-metallic and metallic minerals. At the very commencement [...] |
||||
|
Copyright © 2012 Crystal and stones - All Rights Reserved |
|||||
