lonsdaleite : List Of Minerals : The Stone Network
The Business To Business Portal For The Natural Stone Trade

Premium Black Galaxy Granite Slabs
Direct From The Factory
Ex-India

Mobile

Directory

Stone Fairs

Exhibitions 2017 Country
Exhibitions 2017 By Date

Stone Images

Granite
Limestone
Marble
Onyx
Quartzite
Sandstone
Slate
Travertine

Stone Machines

New Stone Machines
Used Stone Machines

Stone Sites

Stone Forums
Stone Magazines
Stone Portals

Stone Standards

CE Marking

Stone Supplies & Fabricators

Australia
Canada
United Kingdom
U.S.A.

Stone Testing

ASTM
BRE
Sandberg
Stats
Stone Initiatives
UKAS

Petrology

Granite
Limestone
Marble
Quartzite
Sandstone
Slate
Travertine

Rocks

Igneous
List of Minerals
List of Rocks
Metamorphic
Minerals
Sedimentary

Various Resources

A To Z Stone Names
Anti Slip
BIDA
Building Conservation
Building Design
English Heritage
Maintenance Products
Natural Stone Database
RIBA
RICS
Salvo
SPAB
Stone Federation GB
Trade Terminology

Lonsdaleite is a hexagonal allotrope of the carbon allotrope diamond, believed to form when meteoric graphite falls to Earth. The great heat and stress of the impact transforms the graphite into diamond, but retains graphite's hexagonal crystal lattice. Lonsdaleite was first identified from the Canyon Diablo meteorite at Barringer Crater (also known as Meteor Crater) in Arizona. It was first discovered in 1967. Lonsdaleite occurs as microscopic crystals associated with diamond in the Canyon Diablo meteorite; Kenna meteorite, New Mexico; and Allan Hills (ALH) 77283, Victoria Land, Antarctica meteorite. It has also been reported from the Tunguska impact site, Russia.

Lonsdaleite is also known as "hexagonal diamond." It is transparent brownish-yellow in color and has an index of refraction from 2.40 to 2.41, a specific gravity from 3.2 to 3.3, and a Mohs hardness of 78. The Mohs hardness of diamond is 10; the lower hardness of lonsdaleite is chiefly attributed to impurities and imperfections in the naturally occurring material. It can also be created by the thermal decomposition of a polymer, poly(hydridocarbyne), at atmospheric pressure under argon starting at 110 C.

Lonsdaleite was named in honour of Kathleen Lonsdale.

  • Lattice Structure
  • Other allotropes of carbon can be described easily by referencing the base units of their lattice e.g. graphite is layer-upon-layer of flat sheets consisting of benzene rings, where each ring is comprised only of carbon atoms bonded to other carbon atoms through double bonds with angles of 120 degrees between all bonds. However, the difference between lonsdaleite and diamond cannot be explained quite so simply.

    One common misconception is that lonsdaleite consists of a structure comprised only of identical, interlocking cyclohexane rings. However, this is only really true of pure diamond: every atom ring that can be found in the lattice of diamond is shaped identically to that of the most stable cyclohexane ring conformation. Such rings are characterized by their six single bonds, with angles of 109.5 degrees between each bond, and are not flat but instead form a chair structure. This ring structure is the most stable conformation of cyclohexane, and this contributes to the stability of diamond, which is the most stable allotrope of carbon. This stability is responsible for diamond's extreme hardness.

    The structure of lonsdaleite is very similar to that of diamond in that all atom rings found in the lattice have six member carbon atoms linked only by single bonds with 109.5 degrees between each bond. The difference is that not all such six atom carbon rings in lonsdaleite take the form of the chair structure; some rings form in what is called a boat structure (or more correctly a boat conformation) leaving the unbonded distance between non-adjacent carbon atoms smaller than that of the chair structure. This is fundamentally less stable, and causes the hardness of lonsdaleite to be slightly less than that of diamond. Despite the fact that the presence of boat-structure-rings in lonsdaleite is the mineral's defining characteristic, most rings in its lattice still form the more stable chair conformation.

    Trade Supplies
    Information
    Information
  • Absolute Black Granite : Black Galaxy, Star Galaxy, Nero Impala etc. Black is popular, black looks great, black is more expensive >>>
  • Black Galaxy Granite : Quarrying & Quality Information >>>
  • M.I.A. Information
    Copyright :
    Legal Information
    This web site is protected under International Law by the
    Digital Millennium Copyright Act 1998.

    If you wish to link to this site please feel free to do so HOWEVER blatant design copying, code copying and theft of bandwidth will result in legal action!

    Digg Logo ImageDigg Facebook Logo ImageFacebook Reddit Logo ImageReddit StumbleUpon Logo ImageStumbleUpon Twitter Logo ImageTwitter

    Home : Contact : About : Legal : Privacy : Cookies : Copyright 1998-2017 : The Stone Network