File:Birds and nature (1902) (14565526759).jpg

Identifier: birdsnature111902chic (find matches)
Title: Birds and nature
Year: 1900 (1900s)
Authors:
Subjects: Birds Natural history
Publisher: Chicago, Ill. : A.W. Mumford, Publisher
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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ndia. A whitevariety of chalcedony containing minuteblood red spots is known as St. Stephensstone. Chalcedony was formerly usedmuch more and more highly prized thanat the present time. It was especiallyemployed for seals and rings, but alsofor plates, cups and vases. These wereoften engraved in the most elaboratemanner, the hardness and toughnessof the stone making it well adapted forthis purpose. The sentiment of the stoneis: A disperser of melancholy. Thename chalcedony is from Chalcedon, acity in Asia Minor, where the originalchalcedony was found. This mineralwas probably not like our modern chal-cedony, however, being more probablya green quartz. This chalcedony is men-tioned as one of the foundation stones ofthe Holy City in the Book of Revela-tions. Carnelian is a red variety of chalce-dony, sard a brown variety. All grada-tions between these shades of course oc-cur, those of the reddish cast being themost common. The most highly prizedcolor for carnelian is a deep blood red, 74
Text Appearing After Image:
LOANED BY FOOT£ MINERAL CO, QUARTZ (obscurely crystalline.) UUHFORD, CHICAeO. Bloodstone, polished (India.)Tiger Eye, polished (South Africa.) 469 Chrysoprase, polished (Arizona.)Agate uud Carneiiau, polished (Lake Superior.) Jasper (Germany.) Ribbon Jasper, polished (Siberia.) appearing darker red in reflected light.The Hghter red and yellowish shades areless desirable, stones of these shades be-ing known as female carnelians, whilethose of the darker shades are known asmale carnelians. The colors are dueto oxides of iron and can sometimes bechanged by heating. Thus the yellowishand brownish carnelians being colored byiron hydroxide can be changed by heat-ing to red, the water being driven off andiron oxide left. The heating may bedone in the sun or by some other slowmeans. Even olive green stones arechanged in India to red by this process.The color may also be introduced artifi-cially by allowing the stones to lie in amixture of metallic iron and nitric acid,or of iron sulphate for

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