DATOLITE
Specimen dat-4

Dims: 3.3" x 2.3" x 1.4" (8.4 x 5.8 x 3.6 cm)

Wt: 5.79 oz. (164.0 g)

Verchniy Quarry, Dal'negorsk, Primorskiy Kray, C.I.S., Russia

Three individual Datolite crystals rise above the quartz and calcite base of this specimen. The largest of these has dimensions of 2.3 x 1.0 x 0.9" (5.8 x 2.5 x 2.3 cm), and the others are less than half that size. They occur as rather thick monoclinic prismatic crystals that have a pearly luster, and they have a pale green color and are transparent and moderately clear in some areas, though they contain many internal fractures and flaws. There is only a very small amount of visible damage to the crystals, which are all at least partially coated with a thin druse of tiny, intergrown, clear quartz crystals. The base on which the Datolites rest is made up of several clear, hexagonal prismatic quartz crystals that have a matte luster and many shards of calcite that represent broken, bladed crystals.

Dims: 1.9" x 1.6" x 0.8" (4.8 x 4.1 x 2.0 cm)

Wt: 1.11 oz. (31.6 g)

Poona, Maharashtra State, India

One of the more unusual forms of Datolite, this specimen represents a massive form that the mineral takes on rare occasions. There are several other materials in the specimen, though, including a substantial amount of quartz and maybe a bit of basalt rock. One face has been cut into the piece to make viewing easier. The Datolite occurs in an oolitic form, with a color that ranges from an opaque, dark, brick-red to a nearly transparent colorlessness. There is also some material that has the grassy, yellow-green color of pyromorphite, though I am sure that that is not what the material is.

Dims: 2.3" x 1.9" x 0.9" (5.8 x 4.8 x 2.3 cm)

Wt: 1.83 oz. (51.8 g)

La Aurora Mine, Charcas, San Luis Potosi, Mexico

I was surprised at first of the locality of this specimen, but as it is sometimes associated with danburite, I could understand. It consists of a very thin, pyrite-laden crust which is coated with a crust made up of several monoclinic prismatic Datolite crystals. These crystals range in length from 0.1 - 0.6" (0.3 - 1.5 cm) and are all incomplete due either to intergrowth or to the fact that they all have grown out at acute angles; one of the larger crystals appears to have grown nearly parallel to the underlying crust. All the crystals have well-defined edges and smooth faces that show a waxy-to-pearly luster. Their color is a pale green, which is rather common for this mineral. They appear to be transparent and clear to a degree, though the larger crystals are merely translucent due to cloudy inclusions and probable internal fracturing. Scattered on the Datolite cluster are tiny clusters of almost microscopic, white crystals. I do not know what they are, and they are too small for me to effectively discern their crystal form, even under 10-power magnification.

Dims:2.7x1.9x1.1" (6.9x4.8x2.8 cm)

Wt: 3.5oz. (98g)

Delaware Mine, Keweenaw cty., Michigan

This is a nodule of datolite that has been cut and polished on one side. The polished side shows the light to dark brown datolite, light gray impurities, and an interesting spider-web effect of fissures that were filled with a dark colored material. The exterior face shows the nodular form of the datolite.

Dims:1.4x0.9x0.5" (3.6x2.3x1.3 cm)

Wt: 0.4oz. (12g)

Knowlton Lode, Caledonia Mine, Ontonagon cty., Michigan

This specimen consists of a nodule of massive datolite that has been partially polished. There are faint banding marks visible on the polished section showing that the datolite was deposited in layers. There is a thin vein of copper along the bottom of the nodule. This specimen is undamaged.

Dims:1.3x1.1x0.3" (3.3x2.8x0.8 cm)

Wt: 0.9oz. (26g)

Delaware Mine, Keweenaw cty., Michigan

This is a two-piece specimen. It consists of two pieces of a nodule of datolite that has been cut and polished on one side. The two pieces do not match-they are from seperate nodules, or perhaps each side of a larger nodule. One side on each piece has been broken away. There is some iron staining visible in the polished sides.

Dims: 5.19x3.30x2.05" (13.19x8.39x5.21cm)

Wt: 19.43oz (550g)

Dalnyegorsk, Russia

This is a very nice cabinet specimen of datolite. It has a complex shape and is likely three or more intergrown crystals. It is pale green with a vitreous luster, and is translucent. Some surfaces are slightly dulled by tiny pits, while others show interesting growth patterns. Some of the pits have a dark filler, and parts of the bottom and a side appear dirty.