Message #37249

[Peter Bentley 彭达理]

Hi All

In Chinese  - as   far  as  I am  aware -   "crystal"  aka   quartz   is   水 晶

From then  on  the only  differentiation in Chinese  is   as to whether  it  is  natural crystal  (i.e.  rock  quartz) or   man-made crystal,  but  both  are  chemically  the  same 

As to whether they  have a  different  thermal conductivity   and/or   specific heat (which are the  only  possible  explanations  for  what  Joey calls the "cheek"  test)   I am   not  sure.

I  forget my  chemistry  in  detail  but as  far as  I  recall  "lead glass" is  just  one  variety - although a  top class  variety -  of  "glass"  in general.    But to make   things  more  confusing ,  "lead  glass" is  often  referred to  as "crystal  glass"    e.g.  as  in  a  typical  advertising  blurb :  " these   fine-cut ,  carved  wine   glasses  are   made  of (lead) crystal  glass"

From  Google :  Lead glass is a variety of glass in which lead replaces the calcium content of a typical potash glass. Lead glass contains typically 18–40 weight% lead(II) oxide (PbO), while modern lead crystal, historically also known as flint glass due to the original silica source, contains a minimum of 24% PbO.

GEORGE :  You  are the  expert  on this ! 

Cheers
Peter

PS :

GEOFF : Unless  it's a  photographic mistake  that  bottle  seems to have  greyish   streaks in the  material. If  so  it  must  be   real   natural  rock crystal (quartz)  because  one of the   distinguishing  features  of  natural  crystal (quartz)   is that it  often  - indeed usually -  has  tiny  imperfections, whereas  man-made crystal (quartz)  is  defect-free.