Magmatic, metamorphic, pegmatitic, and alluvial rocks. Zicons are commonly slightly radioactive due to trace amounts of uranium and make prime, geochron age indicators.
IMA Status:
Valid Species (Pre-IMA) Prehistoric
Locality:
Laacher See, Niedermendig, Germany. Link to MinDat.org Location Data.
Name Origin:
Named from its containing the element, zirconium; which was named from the Persian, zar "gold" and gun = "like" which translates "like gold".
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Physical Properties of Zircon
Cleavage:
{110} Indistinct
Color:
Brown, Reddish brown, Colorless, Gray, Green.
Density:
4.6 - 4.7, Average = 4.65
Diaphaneity:
Transparent to translucent to opaque
Fracture:
Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Habit:
Crystalline - Fine - Occurs as well-formed fine sized crystals.
Habit:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Habit:
Tabular - Form dimensions are thin in one direction.
Hardness:
7.5 - Garnet
Luminescence:
Fluorescent, Short UV=yellow,green orange, Long UV=yellow, green orange.
Luster:
Adamantine
Streak:
white
Optical Properties of Zircon
Dichroism (e):
colorless.
Dichroism (w):
colorless.
Gladstone-Dale:
CI meas= -0.034 (Excellent) - where the CI = (1-KPDmeas/KC) CI calc= 0.008 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1991,KPDmeas= 0.2076,KC= 0.2007 Ncalc = 1.92 - 1.97
Bulk Density (Electron Density)=4.52 gm/cc note: Specific Gravity of Zircon =4.85 gm/cc.
Fermion Index:
Fermion Index = 0.07 Boson Index = 0.93
Photoelectric:
PEZircon = 132.43 barns/electron U=PEZircon x relectron= 598.38 barns/cc.
Radioactivity:
GRapi = 3,773.15 (Gamma Ray American Petroleum Institute Units)
Concentration of Zircon per GRapi unit = 265.03 (PPM)
Zircon is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.
Estimated Radioactivity from Zircon - mild
Specimen Size Weight/Volume (Sphere) *
Calculated Activity Bequerols (Bq)
Calculated Activity Curies (Ci)
Estimated Activity GR(api)
Estimated Exposure (mRem**)/hr If Held in Hand For One Hour
1000 gm / 7.33 cm
85,050
2.30E-06
3,773.15
1.24
100 gm / 3.40 cm
8,505
2.30E-07
377.31
0.12
10 gm / 1.58 cm
851
2.30E-08
37.73
0.01
1 gm / 7.33 mm
85
2.30E-09
3.77
0.00
0.1 gm / 3.40 mm
9
2.30E-10
0.38
0.00
0.01 gm / 1.58 mm
1
2.30E-11
0.04
0.00
0.001 gm / 0.73 mm
0
2.30E-12
0.00
0.00
Weight of pure Zircon in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.85 gm/cc.*
Goverment Estimate of Average Annual Exposure (
360 mRem)
** Note: 10 microsieverts/hr = 1 mRem/hr **
Max Permissable Adult Dose 50,000 mRem/yr (hands), 15,000 mRem/yr (eyes)
Lethal Dose LD(50) Exposure 400,000 to 500,000 mRem
Estimated Thorium Activity ( 0.19 % Th) From Sum REE Elements ( 3.78 % REE)
Zircon Classification
Dana Class:
51.05.02.01(51)Nesosilicate Insular SiO4 Groups Only
Chemical Formula: 
- mild