Blue John
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Physical & Optical Properties
Category
Semi-Precious Gems
Mohs Hardness
4.0
Specific Gravity
3.0 – 3.25
Refractive Index
1.432 – 1.436
Crystal System
Isometric
Luster
Vitreous
Cleavage
Perfect
Color
various
Mohs Hardness
| Mohs | Reference mineral | Blue John |
|---|---|---|
| 1 | Talc | |
| 2 | Gypsum | |
| 3 | Calcite | |
| 4 | Fluorite | ● |
| 5 | Apatite | |
| 6 | Orthoclase | |
| 7 | Quartz | |
| 8 | Topaz | |
| 9 | Corundum | |
| 10 | Diamond |
Crystal System
Value & Market
Price Tier
Budget (< $50/ct)
Where to Buy Blue John
Blue Nile
Fine jewelry retailer
James Allen
Gemstone jewelry
Brilliant Earth
Ethically sourced gems
Amazon
Wide selection
Links may earn a commission at no extra cost to you.
Treatments
4Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
3.00 to 3.25Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
PerfectHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
1.432 to 1.436Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
IsotropicUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Banded white/purpleGemdat.org, Management Team (2012)
Transparent,TranslucentArthur Thomas, Gemstones (2009)
VitreousArthur Thomas, Gemstones (2009)
IsometricHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Cubic, massiveArthur Thomas, Gemstones (2009)
Blue John information at mindat.org
UK
[www.thamesvalleyminerals.com]
Fluorite: The Collector's Choice. Extra Lapis English No. 9
About Blue John
ブルージョンはイングランドのデービーシャー州キャッスルトンのブルージョン洞窟とトリーク崖洞窟でのみ産出する稀少な縞模様の蛍石変種です。紫・青・黄の独特の縞模様を持ち、18世紀から花瓶や装飾品の素材として珍重されてきました。年間の採掘量は500kgに限られ、その稀少性と歴史的価値から英国の地質遺産として保護されています。
On this page
Jewelry Use
Durability
3/10
Science FYI Family
Frequently Asked Questions
What is Blue John?
ブルージョンはイングランドのデービーシャー州キャッスルトンのブルージョン洞窟とトリーク崖洞窟でのみ産出する稀少な縞模様の蛍石変種です。紫・青・黄の独特の縞模様を持ち、18世紀から花瓶や装飾品の素材として珍重されてきました。年間の採掘量は500kgに限られ、その稀少性と歴史的価値から英国の地質遺産として保護されています。
What is the hardness of Blue John?
Blue John has a Mohs hardness of 4.0, making it relatively soft for use in jewelry.
What color is Blue John?
Blue John is primarily Various.
How much does Blue John cost?
Blue John falls into the Budget (< $50/ct) price range. Prices vary based on color, clarity, cut, and origin.
What is the crystal system of Blue John?
Blue John belongs to the Isometric crystal system.