This site was last updated on June, 2010.
Quartz Crystal Habits within Herkimer Diamond Deposits
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Larger photos of the thumbnails presented on the main "Crystal Form" page. Included is identification information and the source link is embedded there (just click). Additional information and comments are provided for each photo.
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Small quartz druze in various forms & colors
To the left, is a specimen (6 cm across) with a coating of pyramidal white "normal" druze with some carbon on top. The pyramidal shape is like rows of little mountain peaks (which you can see in the photo below). This is from Fonda, NY (DA) and actually difficult to find there as most of the white druze is coated with a second smokey druze - some of which you can see on the right side. Most often the smokey druze will simply duplicate (as an overgrowth) the shape of the earlier white druze. Photo DrD, 2008.
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The specimen below is a close up of a small thumbnail (and just about the size of a thumbnail) specimen (15mm across). It is of a longer prismatic druze that always follows an ealier druze. It often has carbon inclusions, and often is smokey (but it can be clear, white or rust covered). The photo is enlarged to help the viewer see the elongated prismatic form. The elongated form is a bit more dificult to see in the next two photos. This is from DA and rare from that location. Photo DrD, 2008.
The specimen below is also from Fonda. NY (DA - 1989). The specimen is 4 cm across and is a nice example of the association overlaping two druze events, one on top of the other, and then the Herkimer event last. Photo DrD.
<- Second prismatic druze
To the left is black pyramidal druze from Middleville, NY (HDM). Specimen is 7 cm long. Black druze is not common for the entire Herkimer district, but more common from this location. Is is caused by carbon inclusions and coatings. This specimen was much blacker before it was cleaned due to a light carbon dusting that washed off. Photo DrD., 2008
To the right is an example of both black druze and white druze. On close examination both the white and the black are of the same crystal formation and appear to have formed at the same time. The difference in "blackness' is due to the amount of carbon material available to the crystals during the time they formed. In addition, since some have a black dust as a coating (which does wash off) it appears that there was movement of carbon material in the pockets after the quartz druze was formed. This specimen is from Middleville, NY (H.D. Mine) and is 7 cm tall. Photo DrD. 2008
Druze comes in several different colors, shapes and relationships to the history at each Herkimer diamond deposit. Of interest - there are layers of rock with druze and Herkimer diamonds and there are also layers without druze that contain just Herkimer diamonds (see matrix photos). Druze behavior is not the same across the Herkimer district, and sometimes not even across a single deposit. There are basically three types of druze, sometimes overlapping each other and sometimes as separate distinct coatings. There is the early "snowball" druze that is likely tied to the the primary pyramidal druze. Combined these two druze forms represent the first major quartz events in the Herkimer district. Then there is the secondary prismatic druze. Then finally the third "Baby floater" druze, which appears to have overlaped with the end of the prismatic druze phase and the beginning of the Herkimer phase and can be seen in the druze at the Ace of Diamonds mine, which has a distinctive sparkling dark amber appearance.
The most common form of druze is one that has a smokey color to it. This can range from a pale tint of color (see prismatic druze below) to the dark color in the specimen shown here. There is also a range in crystal size with most druze size looking like the above photo. The very dark smokey druze below is unusual for its size and color, and it has a "tinted" herkimer to go with it. The specimen is 7 cm across and is from Fonda, NY (DA - 2006). Photo DrD.
To the left, is a close up photo of a coating of pyramidal white "normal" druze showing the pyramidal shape. This is from Fonda, NY (DA) and actually difficult to find there as most of the white druze is coated with a second smokey druze (see the photo below). Photo DrD.
The specimen below is also from Fonda. NY (DA - 2008). The specimen is 4 cm across and is a nice example of the association overlaping two druze events, one on top of the other. What is different is that the first druze phase is broken near the bottom of the photo exposing the white color of the first druze coating. It is interesting that when this second druze appears on the early white druze it is often is preceded by some type of coating (clay?) covering the first druze. This association is fairly common (once you begin to look for it). Photo DrD.
How many other Herkimer deposit locations show this two layer druze association of both pyramidal and prismatic? And what does it look like?
The photo below is a microscope photo of the above specimen and shows some of the textures more clearly. The white coating on the first druze is quite evident.
Web page author - W. David Hoisington, Ph.D.
The two photos below show these longer prismatic druze lying in rows, like boards of a fence. They are also lie over the pyramidal points of the earlier druze - which in these photos are coated (clay?) and not crystal white. These prismatic crystals are about 1/2 the size of the crystals in the above photo. Specimens are from Fonda, NY. (DA - 2006 and 2008). This crystal form is very rare for that locale. Photos by DrD.
Second Phase Prismatic Druze
To the left is a close up photo of the flat black druze specimen shown above, but this is a side view. The importance of this picture is that it clearly shows the white "rind" that often underlies the primary black or smoky pyramidal druze. Sometimes it is well developed and laminations can be seen, much like tree rings. Other times it is poorly developed. This "rind" feature is not associated with the second phase prismatic druze (although some clay and disolution of minerals may be associated with the second phase) and it is not associated with the "baby floater" druze. See the discussion of this on the babyfloater druze page. Photo DrD, 2008.
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Baby Floater" Druze Click Here ->
Primary Pyramidal Druze - First Phase
A side photo, close up, of this specimen is provided below.
Below is a photo of a specimen from TCR (8 cm long, photo by Dr. D. 2009). What can be seen here are the same features as shown in the above photo except on a larger surface and the first druze is not clay covered. Below, the first druze is pyramidal, and cream color. It is encirled by a second druze that is more prismatic, but also includes "baby herkimers". In addition the small mounds of the first druze, when broken, are often hollow (not always the case but more often than not what the second druze is present). Because the first phase here is snowball looking it can be called "Snowball druze". The black is the carbon material.
It is posible that across the district (except HBQ) this two druze phase association is present in some form.
Specimen from Turtle Clan Ridge showing "blue" druze - first phase. Also an excellent example of saddle dolomite. Specimen is 5 cm across. Photo by Dr. D. 2009. The bluish color may be due to weathered chalcopyrite forming a bluish secondary copper mineral. Such bluish material has been seen at this location and at HBQ. The "rust" streaks also indicate the iron sulphides were likely present.
To the right, the specimen is 9 cm across, from Turtle Clan Ridge (TCR), photo Dr. D. 2009. This is a first phase pyramidal druze. The difference is that the the crystals did not grow very much and look like a sparkling coating of snow. Since this is an early phase of mineral deposition it is often affected by all the events that follow (and there are many). Finding pristine samples of "snowball druze" is not easy, but it may be that altered samples are present in many locations if they can be recognized as such.
One can also ponder on the the shape of this unique druze and how it mirrors the shape of some rounded wall rock found within larger Herkimer diamond pockets. Why is this rounded texture so common?
Third Phase Druze - Baby Herkimers
In the above photo the second druze (that rims the "snowball druze") is mixed in with "baby herkimers". This forms a druze coating in most of the Herkimer mines throughout the district. This third druze phase is probably not officially a druze but it is often interwoven with the second prismatic phase and sometimes forms a coating all by itself. It is also important field evidence regarding the formation Herkimer diamonds. Because this phase of quartz mineralization is so important to the history of Herkimer diamond formation it deserves its own web page. Click on the link below.
Below is a close-up of the above photo. You can see the sparkle of the pyramidal points in the "snowballs". You can also see the mixture of baby Herkimer diamonds, with some prismatic crystals, forming rims around the snowballs. (photo DrD, 2009)
The baby floater druze is the third druze phase and it is discussed below.
The photo below (specimen from TCR, 5mm across) shows how the prismatic druze will often grow in parallel groups, This specimen has not been cleaned. (Photo DrD, 2009)
This parallel growth pattern is shown in the next series of photos.
The above photo is of a specimen from TCR (4 cm across). There is a rusty quartz druze coating over a darker pyramidal druze (the P arrow helps to find a nice example of one pyramidal crystal point). This druze is a unique variation of the prismatic druze where the primatic form is elongated and the growth is not parallel but random. Like a pile of sticks. This specimen was in a host rock that was so "eroded" that it was very light, all brown and filled with holes. Go to the hyrothermal page for a discussion. A close-up of the "sticks" is shown below.
It may be that the "snow" appearance is due to a white coating over the pyramidal druze. This can be seen in the photo to the right. This specimen is from Fonda, NY (DA), Collected 2009, photo DrD 2009.
It is also possible, as we see with all the druze phases across the Herkimer Mining District, that the size of the crystals formed does vary. And perhaps both are happening (coating changes and size variation).
In several (not all) of the Herimer diamond deposits, within the Herkimer diamond mining district, there are zones (mostly horizontal) that contain this first druze. Below is a picture of such a druze zone (TCR - phot Dr. D. 2009). The glove is for scale. You can clearly see druze cavities in the upper left and just right of upper center. Scan the photo carefull and you will see more, along with white veins. This is common for what is locally called "the druze layer".
Some of the Herkimer diamond deposits (like AD and HBQ) do not show the development of the first druze phase but instead show the presence of the second and third druze phases which are described below.
The photo to the right shows a grey/smoky pyramidal (1st phase) quartz overlain by a prismatic druze. You can see a band of this druze at the bottom. The specimen is from TCR, and it is the only location in the Herkimer district where such a crystal habit is found. Photo Dr. D., 2010 - 7 cm across. Specimen collected with permisssion from the mine owners, 2009.
Close up views of this specimen are shown below. Note the etching of the 1st phase quartz.
Please note that the black rods which for the base of scepter crystals in the herkimer district are also this prismatic phase. See the inclusions page and the Scovil page.
