Crystal Lattice Structures:	Creation Date: 13 Jun 2006
	Last Modified: 13 Jun 2006

The Naumannite (Ag₂Se) Structure

You can now

• see the structure from several perspectives;
• examine the structure with an external viewer; or
• download the coordinates of the atoms in these pictures in XYZ format.
• visualize the structure (Uses the JMOL Applet)

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• Pearson's Handbook says that this form of Naumannite is stable below 406K. It also lists another from of the structure which we will add to the database at a later date.
• The positions given by Wiegers, and repeated in the American Mineralogist Crystal Structure Database, are shifted by ( ¼ ¼ 0 ) from those given in Pearson's Handbook. We use the Pearson reference which matches the standard form of the space group as found, e.g, on the Bilbao Crystallographic Server.
• Note that there is only one Wyckoff position for space group P2₁2₁2₁.
• The pictures were generated by replacing the Ag-II atoms with gold atoms to clearly show the inequivalent atoms.

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• Prototype: Ag₂Se
• Pearson Symbol: oP12
• Strukturbericht Designation: none
• Space Group: P2₁2₁2₁ (Cartesian and lattice coordinate listings available)
• Number: 19
• References:
  • G. A. Wiegers, American Mineralogist 56, 1882-8 (1971).
  • Pearson's Handbook, Vol. I, p. 626.
• Primitive Vectors:

  A1	=	a X
  A2	=	b Y
  A3	=	c Z

• Basis Vectors:

  B1	=	+ x1 A1 + y1 A2 + z1 A3	=	+ x1 a X + y1 b Y + z1 c Z	(Ag-I)	(4a)
  B2	=	+ (½ - x1) A1 - y1 A2 + (½ + z1) A3	=	+ (½ - x1) a X - y1 b Y + (½ + z1) c Z	(Ag-I)	(4a)
  B3	=	- x1 A1 + (½ + y1) A2 + (½ - z1) A3	=	- x1 a X + (½ + y1) b Y + (½ - z1) c Z	(Ag-I)	(4a)
  B4	=	+ (½ + x1) A1 + (½ - y1) A2 - z1 A3	=	+ (½ + x1) a X + (½ - y1) b Y - z1 c Z	(Ag-I)	(4a)
  B5	=	+ x2 A1 + y2 A2 + z2 A3	=	+ x2 a X + y2 b Y + z2 c Z	(Ag-II)	(4a)
  B6	=	+ (½ - x2) A1 - y2 A2 + (½ + z2) A3	=	+ (½ - x2) a X - y2 b Y + (½ + z2) c Z	(Ag-II)	(4a)
  B7	=	- x2 A1 + (½ + y2) A2 + (½ - z2) A3	=	- x2 a X + (½ + y2) b Y + (½ - z2) c Z	(Ag-II)	(4a)
  B8	=	+ (½ + x2) A1 + (½ - y2) A2 - z2 A3	=	+ (½ + x2) a X + (½ - y2) b Y - z2 c Z	(Ag-II)	(4a)
  B9	=	+ x3 A1 + y3 A2 + z3 A3	=	+ x3 a X + y3 b Y + z3 c Z	(Se)	(4a)
  B10	=	+ (½ - x3) A1 - y3 A2 + (½ + z3) A3	=	+ (½ - x3) a X - y3 b Y + (½ + z3) c Z	(Se)	(4a)
  B11	=	- x3 A1 + (½ + y3) A2 + (½ - z3) A3	=	- x3 a X + (½ + y3) b Y + (½ - z3) c Z	(Se)	(4a)
  B12	=	+ (½ + x3) A1 + (½ - y3) A2 - z3 A3	=	+ (½ + x3) a X + (½ - y3) b Y - z3 c Z	(Se)	(4a)

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Structures indexed by: Strukturbericht Symbol Pearson Symbol Space Group Prototype

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