
1) Sandstone 2) Sapphire
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https://www.crosswordclues.com/clue/bluestone

Bluestone is a cultural or commercial name for a number of dimension or building stone varieties, including: ==Bluestone of Stonehenge== The term `bluestone` in Britain is used in a loose sense to cover all of the `foreign` stones at Stonehenge. It is a `convenience` label rather than a geological term, since at least 20 different rock types...
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http://en.wikipedia.org/wiki/Bluestone

• (n.) Blue vitriol. • (n.) A grayish blue building stone, as that commonly used in the eastern United States.
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http://thinkexist.com/dictionary/meaning/bluestone/

(from the article `Stonehenge`) ...by a ring of tall sarsen uprights, all originally capped by horizontal sarsen stones in a post-and-lintel arrangement. Within the sarsen stone ...
Found on
http://www.britannica.com/eb/a-z/b/82

(In topic `E-Business Solutions`) Bluestone Software`s Total-e-Business product suite provides companies with an e-Business platform and solution.
Found on
http://www.encyclo.co.uk/local/20477

A blue to bluish-green argillaceous metamorphic sandstone of even texture and bedding, historically quarried neat the Hudson River.
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http://www.encyclo.co.uk/local/22192
Blue'stone` noun 1. Blue vitriol.
Dunglison. 2. A grayish blue building stone, as that commonly used in the eastern United States.
Found on
http://www.encyclo.co.uk/webster/B/70

A hard sandstone of characteristic blue, olive green, gray and buff colors quarried in the states of New York and Pennsylvania (historically quarried near the Hudson River, Appalachian Plateau). Bluestone is most commonly purchased for use as flagstone and other forms of paving.
Found on
http://www.selectstone.com/architectural-resources/stone-glossary/

Copper II sulfate pentahydrate
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http://www.translationdirectory.com/glossaries/glossary071.htm

[
n] - bluish-gray sandstone used for paving and building
Found on
http://www.webdictionary.co.uk/definition.php?query=bluestone
noun bluish-grey sandstone used for paving and building
Found on
https://www.encyclo.co.uk/local/20974

A dense, hard, fine-grained, commonly feldspathic sandstone or siltstone of medium to dark or bluish-gray color that splits readily along original bedding planes to form thin slabs. Bluestone is not a technical geologic term. It is considered to be a variety of flagstone, the thin relatively smooth-surfaced slabs being suitable for use as flagging....
Found on
https://www.encyclo.co.uk/local/22191

a bluish, argillaceous sandstone used for building purposes, flagging, etc.
Found on
https://www.infoplease.com/dictionary/bluestone
No exact match found.