# Homework Help: Metallic lustre

1. Aug 12, 2007

### jordyjordyjordy

hey does anyone know how you can carry out an experiment to find out if a metal or non-metal has a metallic lustre???

i have tried looking all over the internet but i cant find anything...
if u could post answers or terms i can place into the google search panel it would be greatly appreciated

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Aug 12, 2007

### Astronuc

Staff Emeritus
Well it is apparently difficult to find online a discussion of how to determine the 'lustre' of a metal or mineral.

Here is a discussion of 'lustre', but in addition to metallic there are other classifications: adamantine, vitreous (like glass), resinous (like amber), waxy (like jade), greasy (like soapstone), pearly, and silky.

http://en.wikipedia.org/wiki/Lustre_(mineralogy)

http://www.1911encyclopedia.org/Mineralogy [Broken]

Introduction to Mineralogy
http://isis.ku.dk/kurser/blob.aspx?feltid=84117 - this might be useful in conjunction with the others.

See slide 14/16 - Lustre

Coefficient of reflectivity: R = [(n-1)2+n2K2]/[(n+1)2+n2K2]
n = refractive index, K = coefficient of absorption
R is proportional to both!

Types of lustre and examples:
Metallic (gold, graphite, galena, chalcopyrite, pyrite, hematite, magnetite)
Submetallic (sphalerite, ilmenite)
Adamantine (diamond, sphalerite, corundum, goethite, biotite)
Vitreous (rutile, halite, calcite, aragonite, dolomite, apatite, olivine, quartz)
Resinous (sphalerite, apatite, opal)
Pearly (aragonite, gypsum, muscovite)
Greasy (serpentine, nepheline)
Silky (goethite, gypsum, serpentine)
Earthy (graphite, hematite, goethite, kaolinite)

Spectroscopy seems to be the answer, otherwise one must use one's eyes and learn the skill from a experienced mineralogist/metallurgist/material scientist.

Last edited by a moderator: May 3, 2017