Last Updated: Apr 21, 2018     Views: 33556

The answer to this question depends on the kind of glass you are interested in. Below we provide an explanation from The Corning Museum of Glass Research Scientist Emeritus Robert Brill, along with additional resources, including excerpts from George Morey's 1938 book The Properties of Glass, a list of books on the composition of glass, and a link to a Rakow Library research guide on color. You should also check out the article "Chemistry of Glass" in All About Glass on the Museum's website.


Explanation from Dr. Robert Brill, Research Scientist Emeritus

"There are many different kinds of glass. Glass is best described as a state of matter, not as a compound or mixture having one special chemical composition. Literally hundreds of thousands of glasses with different chemical compositions have been made, and each of them has its own set of physical properties as determined by its own chemical composition. Even so, they all share certain properties in common that are the result of their having similar structures at a molecular level. Glasses combine some of the ordinary properties of crystalline solids with some of the properties of liquids but without being either crystalline solids or liquids.

Most glasses ... contain certain elements. These elements are usually described in terms of their oxides. Those most commonly used are:

  • Si, silicon. The oxide is SiO2, silicon dioxide. Ordinarily the SiO2 is introduced as sand.

  • Na, sodium. The oxide is Na2O. It is introduced as a white powder called soda ash.

  • Ca, calcium. The oxide is CaO. It is introduced as limestone, a mineral.

  • Pb, lead. The oxide is PbO. Lead oxide in a glass makes it shiny, brilliant, and heavy.

  • K, potassium. The oxide is K2O. Potassium can be used in place of sodium as a "flux", a substance that allows the sand to be melted at a lower temperature.

Many other elements are used to make glasses with special properties. For example, the following elements can be used to make glasses with the colors described:

  • Fe, iron. Colors glass green.

  • Cu, copper. Colors glass light blue.

  • Mn, manganese. Colors glass purple.

  • Co, cobalt. Colors glass dark blue.

  • Au, gold. Colors glass deep red, like rubies."


Additional Resources

Excerpts from George Morey, The Properties of Glass (1938)

The table below is excerpted from The Properties of Glass by George Morey (1938), p. 80, table 3.2:

Compositions of some Commercial Glasses

 

SiO2

Na2O

K2O

MgO

CaO

PbO

Al2O3

Fe2O2

Belgian Fourcault

70.51

16.74

 

 

10.67

 

1.42

0.16

Flat-drawn window glass,
Libbey-Owens process, European

70.64

17.02

 

0.09

10.58

 

0.77

0.11

Flat-drawn window glass,
Libbey-Owens process, American

72.14

12.60

 

2.62

11.24

 

1.06

0.15

Bottle, light green

64.3

5.87

2.56

5.61

14.73

 

4.89

1.18

Champaign bottle

63.18

9.88

0.36

1.12

14.4

 

8.39

1.93

 

The table below is excerpted from The Properties of Glass by George Morey (1938), p.  76, table 3.1:

Compositions of Some Natural Glasses

SiO2

Al2O3

Fe2O3

FeO

MgO

CaO

Na2O

K2O

H2O+

H2O-

TiO2

Obsidian, Obsidian Cliffs,
Yellowstone National Park

74.7

13.72

1.01

0.62

0.14

0.78

3.9

4.02

0.62

 

 

Obsidian, Cerro de los Navajo,
Tulancingo, Mexico

73.92

12.38

1.62

0.56

0.27

0.33

3.49

5.39

1.69

 

 

Rhyolite glass, Burton Peak,
Nevada

71.6

12.44

1

0.65

0.06

1.9

3.3

4.22

3.78

0.81

0.25

Rhyolite glass,
New South Wales

70.62

11.54

1.2

0.18

0.26

1.72

3.52

1.45

7.24

2.42

0.04

Tektite, Peru

70.56

20.54

 

0.96

0.11

0.78

3.47

3.38

 

 

 

 

Note: The first row is Obsidian from Obsidian Cliffs in Yellowstone National Park. The second row down is Obsidian from Cerro de los Navajo, Tulancingo, Mexico. The third row down is Rhyolite glass, Burton Peak Nevada. The fourth is Rhyyolite glass, New South Wales. The Fifth row down is Tekite from Peru.

 

Books Including Information on the Composition of Glass

If you would like to read more about the composition of glass, a few books on the topic are listed below. Many of these titles are available to borrow from the Rakow via Interlibrary Loan (ILL).

  • Bowman, Sheridan. Science and the Past. Toronto: University of Toronto Press, 1991. (See ch. 3.) Location: Stacks, Call Number: CC75.7 .S41
  • Holscher, Harry H. The Glass Primer. [Place of publication not identified]: Magazines for Industry, 1972. Location: Stacks, Call Number: TP857 .H75
  • Humphrys, Leslie George, and Michael Shoebridge. Glass and Glassmaking. Oxford: Blackwell, 1973. Location: Stacks, Call Number: TP857.3 .H92
  • Scholes, S. R., and C. H. Greene. Modern Glass Practice. Boston: Cahners, 1975. Location: Stacks, Call Number: TP857 .S36 1975
  • Zschimmer, Eberhard. Chemical Technology of Glass. Sheffield: Society of Glass Technology, 2013. (See Book 3. Dependence of physical properties on chemical composition.) Location: Stacks, Call Number: TP857 .Z93ce

 

Books for Young People Discussing the Composition of Glass

 

Related Research Guide

If you would like to read more about coloring glass, consult our Research Guide on Color.


 

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