A field trip to the
Malvern Clay pits
yielded blocks of
lignite with nuggets
of amber
Bauxite Mines
Chapter 8, Page 2
Note: The company is no longer giving permission to collect or visit this site. Alas, but the Federal Government, through one of its mine safety regulatory agencies, and the ever increasing chance of lawsuits, resulting in higher insurance for mining companies, has caused the company to close their mine to collectors, both individuals and groups, since this article was written. So amber is off the list of readily collectible materials from Arkansas.
Going to Acme Brick
Fifteen members of the Hot Springs Geology Club, Inc., went on a field trip to the clay pits of Acme Brick. We met at the Super 8 Motel parking lot at 9:30 and caravaned over to the Perla brick plant on US Highway 270 east of Malvern. James Hagler, mining manager, was kind enough to guide us to the active pit.
We were all excited to have a chance to find amber. The clay mine is located south of the plant site in the Wilcox Group, a series of non-marine interbedded sand, thin lignite, and clay units of Eocene age.
Here's a picture of the amber that I found with a block of lignite, about 4" across.
The Wilcox Group contains the most important commercial beds of clay in Arkansas, being widely used for brick and other clay applications. The mine produces around 400,000 tons of clay per year and supplies two brick plants. It takes 9 scoops of their trackhoe to fill one of the haul trucks (I counted them).
Immediately upon arrival in the pit, everyone began to search for amber . I believe everyone recovered some good specimens of amber during the hour and a half we were there. Several people got some pieces over an inch on a side. I recovered a number of smaller pieces and one piece in the host lignitic clay.
Mr. Hagler, on the right, advised several of us on how to look for amber.
Before we left, I discussed lunch plans with the group. Seems that some of us brought our lunch, some of us did not, and some who did bring their lunches left them in their cars at the motel!! So we stopped at a small country grocery store and several folks had sandwiches made and purchased some drinks.
The Brick and Tile Pit
Then we drove the short distance to the Old Malvern Brick and Tile pit, the now abandoned site of clay mining, for a picnic.
At this site, we were in the same group of rocks, but a variety of features are more readily observed because rain has washed off the outcrops.
Lignite Beds
Several lignite beds are present. The upper one foot of the lignite is often bioturbated (original structure has been destroyed by having been actively worked by small animals while still vegetation) and the holes infilled with clean white sand from the unit deposited directly on top of the lignite bed . A couple of us collected buckets of lignitic clay from under this lignite. The idea is to wash this clay and recover amber from it.
At this site we also saw several horizontally bedded backswamp lignite beds. One of these lignite units was cut through by a river meander and after the meander was cutoff from the main river channel, it slowly began to fill with organic material.
Occasional flooding of the adjacent river brought fine white sand into the cutoff meander. Eventually the meander filled and was covered by a layer of white sand, now somewhat cemented.
In one spot on this site, there is a thin lignite bed that contains abundant leaves in the upper blocky portion of the bed. It is capped by the above mentioned sandstone unit and grades into lignitic clay below.
Don Owens, HSGC club president, is seated at this location where I had previously collected a 5-gallon bucket of lignite blocks to take home and split, looking for fossil leaves Most of the leaves recovered are from deciduous trees, primarily poplar and sparse willow, that grew in the swamps.
The amber trees
The question about what types of trees the amber is from came up once during the trip. For years I had heard the same story, which is that the trees were conifers. But an expert from the US National Museum told John D. McFarland of the Arkansas Geological Commission that most of the amber was from deciduous trees, which to me makes sense because conifers like acid soil, but don't like their feet wet. Plants have not changed too drastically in the past 40 million years. Poplars like very moist soil, but not flooded ground. Willows can handle having their "feet" wet. Just think of some flood plains adjacent to rivers in your area and you have a good idea what the conditions may have been like. I have seen a lot of leaves from this site, but never a fossil imprint of anything coniferous (like needles or cones).
The last of us left the site around 2:00 p.m. as the predicted high of 80 degrees had begun to sap our enthusiasm for additional amber hunting. I think everyone enjoyed the trip!
Ch 8 Page 2
Rockhounding Arkansas revised April 2002
©Rockhounding Arkansas 1998 http://rockhoundingAR.com