Agate

A variety of chalcedony, which is a Quartz.
Considered as a rock consisting of cryptocrystalline silicate.
Is asociated with vulcanic rock and be found in metamorphic rock.
Is used for mortar and chemicals or leather work.
Most of it's use is decorative.

Asociated minerals: calcite, goethite, hematite, quartz, zeolite group

Color: colorless, gray, red, white, pink, blue and many colors, variated with it's impurities
Hardness: 6,5-7 Mohs
Transparent, translucent
Fracture: conchoidal, sub-conchoidal
Quartz density: 2,6-2,65; average 2,62
Quartz Formula: SiO2
Quartz composition: 46,74% silicon; 53,26% oxygen

An pink agate sample

Same agate illuminated from the back

Agate can have fluorescent characteristic when illuminated with ultraviolet light, this pink agate glows orange with small red-violet fluorescent inclusion 

Blue agate

Luminoscence:

General color green, others: white, yellow, orange, blue, red

Green activatorL UO (Uranyl ion) with emiisons in 502,521,544,566,593 nm

Varieties:
Agat-jasper - jasper veins
Agatized coral - a variety of agate replacing coral
Bird's eye agate - agate with bird eye look
Blue Lace Agate - blue-pale bands
Botswana agate - a variety of botswana agate with fine bands, paralel lines and pink blending into white
Brecciated agate - matrix in cement from agate fragments
Cloud agate - gray agate with blured patches and cloudy inclusions
Crazy lace agate - multicolored band agate
Enhydro agate - agate with nods contain water
Eye agate - concentric rings with eye look agate
Fairburn agate - a unique and rare fortified agate
Fortification agate - agate with sharp edges, bands and fortified lines as a castle
Fossil agate - fosile agate / fosil , agate replacing fosil
Haema-ovoid-agates - red colored agate with round patches
Iris agate - shows all spectrum's color when it's on transmitted light
Laguna agate - a colored variety of agate
Lake superior agate - the oldest type of agate with over one bilion years
Mexican lace agate - agate from Mexico
Mocha stone - an agate variety with pyrolusite inclusions
Onyx - Onix - monocromatic / monochromatic agate with black and white bands
Pigeon blood agate - red colored agate - blood agate from Utah
Riband agate - acording to Hey's 3rd Ed , an band colored agate
Sardonyx - a variety of redish agate with black or white bands
Youngite - local name for agate or jasper with druzy quartz crystals

Illuminescence activators: Mn as the most common and for others: Pb, organic impurities, Ce, Sm, Eu, Dy, Tb, Bd, Po, Co
Spectre:
Pb replacing Ca: 320-325 nm
Ce I: 350-355, 380 nm
Ce II: 400 nm
Mn II: 580-620
Mn I replacing Ca: 610-630 nm
St: 400-500 nm and 450-550 nm
Co: 420 nm
Po replacing Co: 570 nm
Nd: 817, 889 nm
Sm: 614, 615, 626 nm
Dy: 483, 577 nm
Tb: 544, 545 nm
Eu I: 591, 618, 696, 709 nm
Eu II: 575 nm
Eu: 592, 619 nm
Spectre: http://www.fluomin.org/galeriespectre/spectre.php?lg=fr&name=CALCITE

Sources:
https://www.minerals.net/mineral/agate.aspx
https://www.mindat.org/min-51.html
http://www.fluomin.org/uk/fiche.php?id=229&name=agate


Other names: agat agate agatul achates