LAPIS
LAZULI
Lapis lazuli is one of the most gorgeous rocks I've
ever seen. The highest quality lapis lazuli in the world is from
northeastern Afghanistan (northern Kuran Wa Munjan District, southern
Badakhshan Province). Lapis lazuli is both Latin & Persian for
Òheaven stoneÓ, or Òsky stoneÓ, or Òblue stoneÓ. This rare rock is
dominated by the deep-blue mineral lazurite, which is a sodalite-group
feldspathoid - (Na,Ca)8(AlSiO4)6(SO4,S,Cl)2. Commonly, whitish streaks of calcite
(CaCO3) and brass-colored specks of pyrite (FeS2) are
present. Lazurite is essentially the most intensely-blue mineral known
(azurite is also consistently intense blue). The intensity of the blue
color in lazurite has been attributed to the sulfur and calcium content.
Lapis lazuli is known from elsewhere in the world, but
northeastern Afghanistan is the classic locality. Afghani material has
been reportedly mined for at least 7000 years. In ancient times, lapis
lazuli was referred to as ÒsapphireÓ.
Pliny the Elder's 37-volume work Naturalis Historiae, or Natural
History, written in about the 70s A.D., refers to Afghani lapis lazuli as "sappiri",
and notes that it has glistening dots of gold in it - see his book 37.
Afghani lapis lazuli comes from the Sar-e-Sang
Deposit, which consists of ~1-8 meter thick and ~20-450 meter long
north-south trending veins, lenses, and layers of lapis lazuli hosted in high-grade
marbles. Stratigraphically, this is the marble member of the Sakhi
Formation, Anglich Group, Sar-e-Sang Series. This material is Late
Archean to early Paleoproterozoic in age (?) (2.4 to 2.7 billion year
metamorphic dates come from Pamir in adjacent Tajikhistan). The lapis
lazuli rocks appear to be the result of retrograde metamorphism and/or
metasomatism (alaskite granite & pegmatite & basic dike intrusions are
nearby). They occur along the eastern limb of the Kokcha Anticline, and
are part of the Fayzabad Metamorphic Massif in the South Badakhshan Block.
The lapis lazuli mines of northeastern Afghanistan are
some of the most difficult-to-access localities in the world, occurring along
steep slopes of deeply carved, narrow river canyons in the northern flanks of
the western Hindu-Kush Mountains. The Sar-e-Sang Mining District
(apparently synonymous with ÒFirgamu MinesÓ) occurs about 1500' above river
water level. The mines are above the lowermost reaches of the Sar-e-Sang
River, a west-flowing tributary of the Kokcha River. This stretch of the
Kokcha River is quite isolated. The nearest villages are Koran-o-Munjan
(to the south) and Robat-e-Payan (to the north). Fayzabad, the nearest
sizable town, is about 100 km to the north-northwest of the Sar-e-Sang Mines.
Location of Sar-e-Sang Mine adits: approximately 36¡ 12.2Õ to 36¡ 14.14Õ North & 70¡
47.85Õ to 70¡ 48.63Õ East.
Access to the Sar-e-Sang Mines is only via narrow foot
trails in a barren, but harshly beautiful landscape. Regarding this area,
British Army Lieutenant John Wood famously said in 1837: "If you do not
wish to die, avoid the Valley of Kokcha."
Lapis lazuli (lazuritic metamorphite) (4.4 cm tall) with lazurite (blue), pyrite (brassy
gold), and calcite (white) from the Precambrian-aged Sar-e-Sang Deposit
of northeastern Afghanistan.