Mindat Logo
Home Page Log In Messageboard The Mindat Directory
Register Search Pages Mineral Chatroom The Mindat Store

Davyne

This page is currently not sponsored. Click here to sponsor this page.
Big Photo

Monte Somma, Somma-Vesuvius Complex, Naples Province, Campania, Italy
© Chinellato Matteo

Show Davyne Photos (34)



Formula:
(Na,K)
 
6
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)(Cl
 
2
,SO
 
4
)
 
2
System:HexagonalColour:Colourless, white
Lustre:VitreousHardness:5½ - 6
Member of:Cancrinite Group
Name:
For Sir Humphrey Davy (1778-1829), English chemist


Cancrinite Group.

Classification of Davyne

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/J.09-20
Nickel-Strunz 10th (pending) edition ID:9.FB.05

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
B : Tektosilicates with additional anions
Dana 8th edition ID:76.2.5.5

76 : TECTOSILICATES Al-Si Framework
2 : Al-Si Framework Feldspathoids and related species
Hey's CIM Ref.:17.10.11

17 : Silicates Containing other Anions
10 : Silicates with sulphate, molybdate or tungstate
mindat.org URL:http://www.mindat.org/min-1238.html
Please feel free to link to this page.

Type Occurrence of Davyne

Type Locality:Monte Somma, Somma-Vesuvius Complex, Naples Province, Campania, Italy
Year of Discovery:1825

Occurrences of Davyne

Geological Setting:Volcanic ejecta and leucite rich lavas.

Physical Properties of Davyne

Lustre:Vitreous
Diaphaneity (Transparency):Transparent, Translucent
Colour:Colourless, white
Streak:white
Hardness (Mohs):5½ - 6
Tenacity:Brittle
Cleavage:Perfect
on (10_10)
perfect to indistinct on {0001}
Fracture:Irregular/Uneven, Conchoidal
Density (measured):2.42 - 2.53 g/cm3
Density (calculated):2.50 g/cm3

Crystallography of Davyne

Crystal System:Hexagonal
Class (H-M):6/m - Dipyramidal
Space Group:P63/m
Cell Parameters:a = 12.705(4) Å, c = 5.368(3) Å
Ratio:a:c = 1 : 0.423
Unit Cell Volume:V 750.40 ų (Calculated from Unit Cell)
Z:1
Morphology:Prismatic crystals to 4cm.

Optical Data of Davyne

Type:Uniaxial (+)
RI values: nω = 1.515 - 1.519 nε = 1.519 - 1.522
Maximum Birefringence:δ = 0.004

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low

Chemical Properties of Davyne

Formula:
(Na,K)
 
6
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)(Cl
 
2
,SO
 
4
)
 
2
Essential elements:Al, Ca, Cl, Na, O, Si
All elements listed in formula:Al, Ca, Cl, K, Na, O, S, Si

Relationship of Davyne to other Species

Member of:Cancrinite Group
Other Members of Group:

- +
Afghanite
(Na,Ca,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(Cl
 
2
,SO
 
4
,CO
 
3
)
 
3
 · 0.5H
 
2
O
Alloriite
(Na,Ca,K)
 
26
Ca
 
4
(Al
 
6
Si
 
6
O
 
24
)
 
4
(SO
 
4
)
 
6
Cl
 
6
Biachellaite
(Na,Ca,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
 
2
(OH)
 
0.5
 · H
 
2
O
Bystrite
(Na,K)
 
7
Ca(Al
 
6
Si
 
6
O
 
24
)(S
 
3
)
 
1.5
 · H
 
2
O
Cancrinite
(Na,Ca,☐)
 
8
(Al
 
6
Si
 
6
O
 
24
)(CO
 
3
,SO
 
4
)
 
2
 · 2H
 
2
O
Cancrisilite
Na
 
7
(Al
 
5
Si
 
7
O
 
24
)(CO
 
3
) · 3H
 
2
O
Depmeierite
Na
 
8
(Al
 
6
Si
 
6
O
 
24
)(PO
 
4
,CO
 
3
)
 
1-x
 · 3H
 
2
O (x<0.5)
Franzinite
(Na,K)
 
6
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
 
2
 · 0.5H
 
2
O
Giuseppettite
(Na,K,Ca)
 
7-8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
,Cl)
 
1-2
Hydroxycancrinite
Na
 
8
(Al
 
6
Si
 
6
O
 
24
)(OH)
 
2
 · 2H
 
2
O
Kircherite
Na
 
5
Ca
 
2
K(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
 
2
 · 0.33H
 
2
O
Kyanoxalite
Na
 
7
(Al
 
6-x
Si
 
6+x
O
 
24
)(C
 
2
O
 
4
)
 
0.5+x
 · 5H
 
2
O (0 < x < 0.5)
Liottite
(Na,K)
 
16
Ca
 
8
(Al
 
6
Si
 
6
O
 
24
)
 
3
(SO
 
4
)
 
5
Cl
 
4
Marinellite
(Na,K)
 
42
Ca
 
6
(Al
 
6
Si
 
6
O
 
24
)
 
6
(SO
 
4
)
 
8
Cl
 
2
 · 3H
 
2
O
Microsommite
Na
 
4
K
 
2
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)Cl
 
2
Pitiglianoite
Na
 
6
K
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
) · 2H
 
2
O
Quadridavyne
(Na,K)
 
6
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)Cl
 
4
Sacrofanite
(Na,K)
 
98
Ca
 
20
(Al
 
6
Si
 
6
O
 
24
)
 
14
(SO
 
4
)
 
26
Cl
 
2
 · 8H
 
2
O
Tounkite
(Na,Ca,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
 
2
Cl · H
 
2
O
Vishnevite
(Na,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
,CO
 
3
) · 2H
 
2
O
Common Associates:
NephelineLeucite
Related Minerals - Nickel-Strunz Grouping):

- +
9.FB.05Afghanite
(Na,Ca,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(Cl
 
2
,SO
 
4
,CO
 
3
)
 
3
 · 0.5H
 
2
O
9.FB.05Bystrite
(Na,K)
 
7
Ca(Al
 
6
Si
 
6
O
 
24
)(S
 
3
)
 
1.5
 · H
 
2
O
9.FB.05Cancrinite
(Na,Ca,☐)
 
8
(Al
 
6
Si
 
6
O
 
24
)(CO
 
3
,SO
 
4
)
 
2
 · 2H
 
2
O
9.FB.05Cancrisilite
Na
 
7
(Al
 
5
Si
 
7
O
 
24
)(CO
 
3
) · 3H
 
2
O
9.FB.05Franzinite
(Na,K)
 
6
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
 
2
 · 0.5H
 
2
O
9.FB.05Giuseppettite
(Na,K,Ca)
 
7-8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
,Cl)
 
1-2
9.FB.05Hydroxycancrinite
Na
 
8
(Al
 
6
Si
 
6
O
 
24
)(OH)
 
2
 · 2H
 
2
O
9.FB.05Liottite
(Na,K)
 
16
Ca
 
8
(Al
 
6
Si
 
6
O
 
24
)
 
3
(SO
 
4
)
 
5
Cl
 
4
9.FB.05Microsommite
Na
 
4
K
 
2
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)Cl
 
2
9.FB.05Pitiglianoite
Na
 
6
K
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
) · 2H
 
2
O
9.FB.05Quadridavyne
(Na,K)
 
6
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)Cl
 
4
9.FB.05Sacrofanite
(Na,K)
 
98
Ca
 
20
(Al
 
6
Si
 
6
O
 
24
)
 
14
(SO
 
4
)
 
26
Cl
 
2
 · 8H
 
2
O
9.FB.05Tounkite
(Na,Ca,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
 
2
Cl · H
 
2
O
9.FB.05Vishnevite
(Na,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
,CO
 
3
) · 2H
 
2
O
9.FB.05Marinellite
(Na,K)
 
42
Ca
 
6
(Al
 
6
Si
 
6
O
 
24
)
 
6
(SO
 
4
)
 
8
Cl
 
2
 · 3H
 
2
O
9.FB.05Farneseite
(Na,Ca,K)
 
56
(Al
 
6
Si
 
6
O
 
24
)
 
7
(SO
 
4
)
 
12
 · 6H
 
2
O
9.FB.05Alloriite
(Na,Ca,K)
 
26
Ca
 
4
(Al
 
6
Si
 
6
O
 
24
)
 
4
(SO
 
4
)
 
6
Cl
 
6
9.FB.05Fantappièite
[Na
 
82.5
Ca
 
33
K
 
16.5
](Si
 
99
Al
 
99
O
 
396
)(SO
 
4
)
 
33
 · 4H
 
2
O
9.FB.05Kyanoxalite
Na
 
7
(Al
 
6-x
Si
 
6+x
O
 
24
)(C
 
2
O
 
4
)
 
0.5+x
 · 5H
 
2
O (0 < x < 0.5)
9.FB.05Balliranoite
(Na,K)
 
6
Ca
 
2
(Si
 
6
Al
 
6
O
 
24
)Cl
 
2
(CO
 
3
)
9.FB.05Carbobystrite
Na
 
8
(Al
 
6
Si
 
6
O
 
24
)(CO
 
3
) · 3.5H
 
2
O
9.FB.05Depmeierite
Na
 
8
(Al
 
6
Si
 
6
O
 
24
)(PO
 
4
,CO
 
3
)
 
1-x
 · 3H
 
2
O (x<0.5)
9.FB.05Kircherite
Na
 
5
Ca
 
2
K(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
 
2
 · 0.33H
 
2
O
9.FB.10Bicchulite
Ca
 
2
(Al
 
2
SiO
 
6
)(OH)
 
2
9.FB.10Danalite
Fe
2+
4
(Be
 
3
Si
 
3
O
 
12
)S
9.FB.10Genthelvite
Zn
 
4
(Be
 
3
Si
 
3
O
 
12
)S
9.FB.10Haüyne
(Na,Ca)
 
4-8
(Al
 
6
Si
 
6
(O,S)
 
24
)(SO
 
4
,Cl)
 
1-2
9.FB.10Helvite
Mn
2+
4
(Be
 
3
Si
 
3
O
 
12
)S
9.FB.10Kamaishilite
Ca
 
2
(Al
 
2
SiO
 
6
)(OH)
 
2
9.FB.10Lazurite
(Na,Ca)
 
8
(Al
 
6
Si
 
6
O
 
24
)(S,SO
 
4
,Cl
 
2
)
9.FB.10Nosean
Na
 
8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
9.FB.10Sodalite
Na
 
8
(Al
 
6
Si
 
6
O
 
24
)Cl
 
2
9.FB.10Tsaregorodtsevite
(N(CH
 
3
)
 
4
)(AlSi
 
5
O
 
12
)
9.FB.10Tugtupite
Na
 
4
(AlBeSi
 
4
O
 
12
)Cl
9.FB.10Helvine
9.FB.15Marialite
Na
 
4
Al
 
3
Si
 
9
O
 
24
Cl
9.FB.15Meionite
Ca
 
4
Al
 
6
Si
 
6
O
 
24
CO
 
3
9.FB.15Silvialite
(Ca,Na)
 
4
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
,CO
 
3
)
Related Minerals - Hey's Index Grouping:

- +
17.10.1Nosean
Na
 
8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
17.10.2Pitiglianoite
Na
 
6
K
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
) · 2H
 
2
O
17.10.3Vishnevite
(Na,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
,CO
 
3
) · 2H
 
2
O
17.10.4Haüyne
(Na,Ca)
 
4-8
(Al
 
6
Si
 
6
(O,S)
 
24
)(SO
 
4
,Cl)
 
1-2
17.10.5Liottite
(Na,K)
 
16
Ca
 
8
(Al
 
6
Si
 
6
O
 
24
)
 
3
(SO
 
4
)
 
5
Cl
 
4
17.10.6Latiumite
K
 
2
Ca
 
6
(Si,Al)
 
11
O
 
25
(SO
 
4
,CO
 
3
)
17.10.7Tuscanite
(K(Ca,Na)
 
6
(Si,Al)
 
10
O
 
22
[SO
 
4
,CO
 
3
,(OH)
 
2
] · H
 
2
O
17.10.8Microsommite
Na
 
4
K
 
2
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)Cl
 
2
17.10.9Delhayelite
(Na,K)
 
10
Ca
 
5
Al
 
6
Si
 
32
O
 
80
(Cl
 
2
,F
 
2
,SO
 
4
)
 
3
 · 18H
 
2
O
17.10.10Hydrodelhayelite
KCa
 
2
AlSi
 
7
O
 
17
(OH)
 
2
 · 6H
 
2
O
17.10.12Afghanite
(Na,Ca,K)
 
8
(Al
 
6
Si
 
6
O
 
24
)(Cl
 
2
,SO
 
4
,CO
 
3
)
 
3
 · 0.5H
 
2
O
17.10.13Franzinite
(Na,K)
 
6
Ca
 
2
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
)
 
2
 · 0.5H
 
2
O
17.10.14Giuseppettite
(Na,K,Ca)
 
7-8
(Al
 
6
Si
 
6
O
 
24
)(SO
 
4
,Cl)
 
1-2
17.10.15Sacrofanite
(Na,K)
 
98
Ca
 
20
(Al
 
6
Si
 
6
O
 
24
)
 
14
(SO
 
4
)
 
26
Cl
 
2
 · 8H
 
2
O
17.10.16Chessexite
(Na,K)
 
4
Ca
 
2
(Mg,Zn)
 
3
Al
 
8
(SO
 
4
)
 
10
(SiO
 
4
)
 
2
 · 40H
 
2
O
17.10.17Innelite
Na
 
2
CaBa
 
4
Ti
 
3
(Si
 
2
O
 
7
)
 
2
(SO
 
4
)
 
2
O
 
4
17.10.18Thaumasite
Ca
 
3
(SO
 
4
)[Si(OH)
 
6
](CO
 
3
) · 12H
 
2
O
17.10.19Ellestadite
17.10.20Ellestadite-(Cl)
Ca
 
10
(SiO
 
4
)
 
3
(SO
 
4
)
 
3
Cl
 
2
17.10.21Hydroxylellestadite
Ca
 
5
(SiO
 
4
)
 
1.5
(SO
 
4
)
 
1.5
(OH)
17.10.22Fluorellestadite
Ca
 
5
(SiO
 
4
)
 
1.5
(SO
 
4
)
 
1.5
F
17.10.23Mattheddleite
Pb
 
5
(SiO
 
4
)
 
1.5
(SO
 
4
)
 
1.5
(Cl,OH)
17.10.24Queitite
Pb
 
4
Zn
 
2
(SO
 
4
)(SiO
 
4
)(Si
 
2
O
 
7
)
17.10.25Roeblingite
Pb
 
2
Ca
 
6
Mn
2+
 
(Si
 
3
O
 
9
)
 
2
(SO
 
4
)
 
2
(OH)
 
2
 · 4H
 
2
O
17.10.26Yoshimuraite
Ba
 
2
Mn
 
2
Ti(Si
 
2
O
 
7
)(PO
 
4
)O(OH)
17.10.27Kegelite
Pb
 
8
Al
 
4
(Si
 
8
O
 
20
)(SO
 
4
)
 
2
(CO
 
3
)
 
4
(OH)
 
8
17.10.28Wenkite
(Ba,K)
 
4
(Ca,Na)
 
6
[(SO
 
4
)
 
3
|(Si,Al)
 
20
O
 
39
(OH)
 
2
] · 0.5H
 
2
O
17.10.29Macquartite
Pb
 
3
Cu(CrO
 
4
)(SiO
 
3
)(OH)
 
4
 · 2H
 
2
O
17.10.30Welinite
Mn
2+
6
(W
6+
 
,Mg)
 
2
(SiO
 
4
)
 
2
(O,OH)
 
6

Other Names for Davyne

Other Languages:
German:Davyn
Russian:Давин
Varieties:
Acarbodavyne

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Davyne

Reference List:

- +
Monticelli, T., Covelli, N. (1825): Prodromo della Mineralogica Vesuviana, Napoli.

Haidinger, W. (1827): Über den Davyn, eine neue Mineralspecies, Annalen der Physik und Chemie, Vol. 87/F2-11, 470-474.

Bonaccorsi E., Merlino S., Pasero M.(1990): Davyne: its structural relationships with cancrinite and vishnevite. Neues Jahrbuch für Mineralogie, Monatshefte, H. 3, 97-112.

Canadian Mineralogist (1990): 28: 341-349.

Internet Links for Davyne

Search Engines:
  • Look for Davyne on Google
  • Look for Davyne images on Google
    • External Links:
  • Look for Davyne on Webmineral
  • Look for Davyne on Athena Mineralogy
  • Look for Davyne on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Davyne details from Handbook of Mineralogy (PDF)
    • Mineral Dealers:
  • Top quality minerals from Kristalle of California
  • Rare and Unusual minerals at Mineralogical Research Company
  • Fabre Minerals - search for Davyne specimens
  • Wilensky Fine Minerals
  • Search for Davyne on Well-Arranged Molecules
  • SpiriferMinerals.com - high quality low prices
  • Buy fine minerals and gemstones from Pala International
  • Fine and rare minerals from mintreasure.com
  • Mineral Classics - Worldwide Collector Quality Minerals and Gems
  • Find Davyne on www.crystalclassics.co.uk
  • Buy from David K Joyce minerals
  • High-end worldwide specimens & outstanding customer service
    • Jobs:
  • Mining & Geology Jobs

    • Localities for Davyne

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    Hide Locality List
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Egypt
     
    • Red Sea
    		Bonaccorsi E., Merlino S., Pasero M.(1991): Davyne from Zabargad (St. John's) Island: peculiar chemical and structural features. Acta Vulcanol., 2, 55-63.
    Germany
     
    • Rhineland-Palatinate
      • Eifel
        • Andernach
          • Eich
    		Hentschel, G., Die Mineralien der Eifelvulkane, Weise Verlag München, 1983
        • Laach lake volcanic complex
          • Kruft
    		Brauns, R. ; Uhlig, J., Cancrinit- und Nephelin-führende Auswürflinge aus dem Laacher See Gebiet, N.Jb. Mineral.Geol.Paläonolog., Beil. Band 56, Abt. A, 468-498, 1913
          • Mendig
            • Niedermendig
    		Brauns, R. ; Uhlig, J., Cancrinit- und Nephelin-führende Auswürflinge aus dem Laacher See Gebiet, N.Jb. Mineral.Geol.Paläonolog., Beil. Band 56, Abt. A, 468-498, 1913
    Brauns, R. ; Uhlig, J., Cancrinit- und Nephelin-führende Auswürflinge aus dem Laacher See Gebiet, N.Jb. Mineral.Geol.Paläonolog., Beil. Band 56, Abt. A, 468-498, 1913)
              • Wingertsberg
    		Brauns, R. ; Uhlig, J., Cancrinit- und Nephelin-führende Auswürflinge aus dem Laacher See Gebiet, N.Jb. Mineral.Geol.Paläonolog., Beil. Band 56, Abt. A, 468-498, 1913
          • Niederzissen
            • Glees
    		Brauns, R. ; Uhlig, J., Cancrinit- und Nephelin-führende Auswürflinge aus dem Laacher See Gebiet, N.Jb. Mineral.Geol.Paläonolog., Beil. Band 56, Abt. A, 468-498, 1913
        • Mayen
          • Ettringen
            • Bellerberg volcano
    		[Blass, G., Graf, H.W., Interessante Neuigkeiten über Cancrinit, Fluorit und Fuchsit aus der Vulkaneifel, Mineralien-Welt 12/1, 26-29, 2001] [Lapis, 15 (5), 9-36]
        • Niederzissen
          • Brenk
    		Blass, G., Graf , HW., Interessante Neuigkeiten über Cancrinit, Fluorit und Fuchsit aus der Vulkaneifel, MW 1/2001
          • Burgbrohl
    		Blass, G., Graf , HW., Neufunde von bekannten Fundorten (VI), MW 6/1992
          • Hannebach
    		Hentschel, G., Die Mineralien der Eifelvulkane, Weise Verlag München, 1983
    Italy
     
    • Campania
      • Naples Province
        • Somma-Vesuvius Complex
    		NJMM (1990) (3), 97
            • Ercolano
              • San Vito
            • Pollena - Trocchia area
    		Carati M., 1982. Guida alla mineralogia vesuviana. Guide Calderini, Bologna.
    M. Carati - Guida alla mineralogia vesuviana - Calderini, Bologna, 1982
    [BINON J., BONACCORSI E., BERNHARDT H.J., FRANSOLET A. M. (2004) - The mineralogical status of "cavolinite" from Vesuvius, Italy, and crystallochemical data on the davyne subgroup. Eur. J. Mineral., 16 (3), 511-520] [Russo, M., Punzo, I. (2004): I minerali del Somma-Vesuvio, AMI]
            • Terzigno
    		Luigi Chiappino data
    • Latium
      • Viterbo Province
    		Stoppani, F.S., Curti, E. (1982): I Minerali del Lazio. Ed. Olimpia, Firenze, 154-158
        • Vico Lake
    		No reference listed
    • Tuscany
      • Grosseto Province
        • Pitigliano
    		Liotti L., 1991. I minerali dei vulcani laziali a Pitigliano (Grosseto). Riv. Mineral. Ital., 15 (3): 121-139.
    Mineral and/or Locality
    Search Google
     
    Copyright © Jolyon Ralph and Ida Chau 1993-2012. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
    Current server date and time: 3rd Sep 2012 09:42:57
    Mineral and Locality Search
    Mineral:
    and/or Locality:
    Options
    Fade toolbar when not in focusFix toolbar to bottom of page
    Hide Social Media Links
    Slideshow frame delay seconds