In the sand box

Why would someone want to use sand vs something like slate, concrete, or a solid polymer?

  I just visited Taleisin west of Madison, Wi, Frank Lloyd Wright home.  The base is sandstone boulders, not concrete, and they are raising money to jack the foundation, for the third time since it was built.  Now sandstone and sand are different, as is the requirement for stabilizing a large dwelling vs an audio component, but I do think that there is a lesson contained here.

I tried a 2 " thick piece of Granite from a sink cut out from a countertop under my turntable, it caused severe ringing and the sound in the room was terrible. Staying with the sponge hockey pucks.

I've tried many isolation schemes over the decades, I prefer sand boxes to granite, concrete, various woods, soft and hard plastic products.  The platform which sits on top of the sand is critical, I have platforms made of various thickness aluminum plates, all with vibration sinks attached via structural glue, also have various wood platforms, various thickness maple and baltic birch. Finally the footers, have many to choose from, generally prefer Stillpoints. Finally I have choice of avoiding sand boxes, platforms or footers altogether, components hung from custom built stands via high test monofilament fish line. All isolation solutions editorialize to some extent, the fish line method  editorializes the least. The entire system sits on a large concrete slab over a suspended floor which is reinforced with a number of floor jacks placed in strategic positions.

@hilroy48  (OP). 

Yes, slabs of un-isolated granite are often reported as causing ringing. I use a slabs Of granite for my amp.  I have a  heavy amp stand with spikes to the concrete floor, on top of the stand (under the granite  are a series of elastomer pucks. Then the amp is on top of springs. So the granite added isolated mass to the system.

I use Tiers of Materials and Granite has for a very long time been dependable and has always found a place to be used within a produced structure.

Note: Thickness of Granite is also a consideration in some structures a 1/2inch (10mm) Slab is the preferred over a 2 inch (50mm) Slab, in another Structure a 8i4 inch x 16 inch x 72 inch (100mm x 400mm x 1800mm) Slab has been the Granite  Material that really let the structure show of its full potential, 

Granite is used in the Configurations for the Structure of the Systems Rack which the Vinyl Source is Mounted on, it is used as a Substantial Piece in the Structure to support the Pre > Power Amps and is also used as a Part in the Structure to support the Floor Standing Cabinet Speakers when the ESL Speakers are swapped out of alternative sound experience.

My own experiments proved a very long time ago that when using the commonly readily available materials, using one type only as a Base or Plinth does not create an end sound that can be classed as a betterment.

If an individual does want to experience a single material that is not expensive and can easily be found as a Off Cut, that when used as a Sub-Plinth, will offer a influence to the end sound that many who experience it, have agreed it is offering a a betterment. Is a not too densely packed Chip Board. Try Chipboard mounted on a Toller Bearing Footer, which is easily produced from Teaspoons and Marbles and this might just be enough for certain devices to be much improved for the end sound they are producing. 

Most recent investigations carried out by myself are proving that Granite and other Materials used in the Structures I have created have a competitor, and one that has now commenced to supersede dependable materials used over many years.

That material is a Engineered Wood Product that is a by design a Highly Compressed Board, produced in a Vacuum with a Heat Treatment and dies have Brands that produce it. It is generically referred to as the following in the Industry: 

                Phenolic Resin Impregnated Densified Wood Board

To get the general idea about this type of material have a look at a Brand such as Panzerholz or Permali, but there are other Brands offering near identical manufacturing methods.