Search results
Results from the WOW.Com Content Network
A rough specimen of bloodstone. Heliotropes (from Ancient Greek ἥλιος (hḗlios) 'sun' and τρέπειν (trépein) 'to turn') (also called ematille, Indian bloodstones, or simply bloodstones) are aggregate minerals, and cryptocrystalline mixture of quartz that occurs mostly as jasper or sometimes as chalcedony (translucent).
The Opificio delle pietre dure, literally meaning "Workshop of semi-precious stones", is a public institute of the Italian Ministry for Cultural Heritage based in Florence. It is a global leader in the field of art restoration and provides teaching as one of two Italian state conservation schools (the other being the Istituto Superiore per la ...
2 O 3). Many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used is habit, the form the gem is usually found in. [12] For example, diamonds, which have a cubic crystal system, are often found as octahedrons. [13] Gemstones are classified into different groups, species, and ...
The Marlborough gems were a large collection of jewels (cameos and intaglios) assembled by several Dukes of Marlborough. [1] [2] The collection was composed of more than 730 carved gemstones, including garnets, sapphires, emeralds and many cameos.
A Goa stone or Lapis de Goa was a man-made bezoar that was considered to have medicinal and talismanic properties. Goa stones were made in Goa, India and exported to apothecaries in Europe from the mid-16th to 18th century. [1] Goa stones were manufactured by Jesuits in the late seventeenth century in Goa because naturally occurring bezoars ...
Outside of subsequent retellings of the tale of the Dropa stones no mention has been found of Chu Pu Tei or Tsum Um Nui, or of their academic work. [2] It has also been suggested that neither is a real Chinese name, although starting from the 2000s they are sometimes rendered as Qu Futai and Chen Wenming, respectively.
Cattierite (Co S 2), vaesite (Ni S 2) and hauerite (Mn S 2), as well as sperrylite (Pt As 2) are similar in their structure and belong also to the pyrite group. Bravoite is a nickel-cobalt bearing variety of pyrite, with > 50% substitution of Ni 2+ for Fe 2+ within pyrite. Bravoite is not a formally recognised mineral, and is named after the ...
Pietra serena was very popular in Italian Renaissance architecture, and because of this the quarries where the stone was found were exploited.Numerous quarries surrounding the Florentine region of Italy have been found both under and above ground, and each quarry was distinct in the variety of pietra serena formed there due to the differing style of rock formation.